Red-Coloured Decorative Pigments with High Chroma and High Brilliancy, Method for Their Production and Use of Same

ABSTRACT

The present invention relates to red effect pigments including a nonmetallic substrate in platelet form and a coating applied thereto, wherein the coating includes at least one of metal oxide, metal hydroxide or metal oxide hydrate, the metal ions of the metal oxide, metal hydroxide and/or metal oxide hydrate comprise at least two different metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr, and to a process for production thereof and to the use of the red effect pigments.

The present invention relates to red effect pigments comprising a nonmetallic substrate in platelet form and a coating applied thereto, wherein the coating comprises at least one metal oxide, metal hydroxide and/or metal oxide hydrate, the metal ions of the metal oxide, metal hydroxide and/or metal oxide hydrate comprise at least two different metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr, and to a process for production thereof and to the use of the red effect pigments.

Multilayer pigments which, based on a nonmetallic substrate in platelet form, comprise at least one layer sequence composed of layers of alternately high, low and high refractive index are known, for example, from EP 1 572 812 A1, EP 1 213 330 A1, EP 1 025 168 B2, EP 1 621 585 A2, EP 0 948 572 A1, EP 0 950 693 A1, EP 1 306 412 A1, EP 1 587 881 A2, EP 2 632 988 A1 or EP 1 474 486 A2. Depending on the optical layer thickness of the layer of low refractive index, it is possible for the multilayer pigments to change their visual appearance depending on the viewing angle, as described, for example, in EP 1 375 601 A1, EP 1 281 732 A1, EP 0 753 545 A2, US 2004/0003758 A1. A common factor in all the applications cited above is that the layer sequence includes a layer of low refractive index composed of a metal oxide of low refractive index, for example silicon oxide.

Compared to monolayer effect pigments with just a single identical first layer, multilayer pigments feature higher gloss and in some cases higher chroma, naturally assuming that the substrate and particle size here are the same.

EP 1 422 268 A2 discloses a pigment with multilayer structure, said pigment having two or more metal oxide layers, wherein the at least one metal (ion) of the metal oxide layer is selected from the group consisting of cerium, tin, titanium, iron, zinc and zirconium. The aim of this application is pigments having high chroma and high brilliance, and having a minimum number of pores of minimum size in their coating. According to EP 1 422 268 A2, a low pore volume is said to assure a coating of high visual quality.

US 2015/0344677 A1 relates to effect pigments based on coated substrates in platelet form. The coating comprises first and second layers of high refractive index, and a third component which is intended to diffuse partly or to an extent of 100% into one or both of the layers of high refractive index. The third component may be SiO₂ or another metal oxide. The aim of this application, in the case of effect pigments having a D₅₀ of 15 μm or less, is to obtain coverage with SiO₂ without agglomeration.

It was an object of the present invention to provide a red high-chroma pigment having high gloss and high hiding power, which has a red interference color, high mechanical stability and high chemical stability and is simultaneously producible with low material input in a very simple manner.

This object is achieved by provision of a red effect pigment comprising a nonmetallic substrate in platelet form and a coating applied to the substrate, wherein the coating comprises at least one metal oxide, metal hydroxide and/or metal oxide hydrate, the metal ions of the metal oxide, metal hydroxide and/or metal oxide hydrate comprise at least two different metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr, the proportion of iron ions, determined by means of XRF and calculated as the elemental iron, totals at least 17% by weight, based on the total weight of the red effect pigment, and where the hue angle h*15 in the CIE LCh color space is within a range from 320° to 360° and 0° to 60°.

Preferred developments of the red effect pigment are specified in dependent claims 2 to 9.

The object is additionally achieved by provision of a process for producing the red effect pigment of the invention, wherein the process comprises the following steps:

-   (i) optionally applying an uncalcined layer comprising or consisting     of tin oxide, tin hydroxide and/or tin oxide hydrate to the     nonmetallic substrate in platelet form, -   (ii) sequentially applying three uncalcined layers A, B and C each     consisting of or comprising at least one metal oxide, metal     hydroxide and/or metal oxide hydrate, where the metal ion of layers     A and C respectively comprises or is at least one metal ion selected     from the group of metals consisting of Fe, Ti and Zr, the metal ion     of layer B comprises or is at least one metal ion selected from the     group of metals consisting of Sn, Ti and Zr, at least one metal ion     of layers A and/or C comprises or is an iron ion, layers A, B and C     are arranged directly one on top of another, and where the at least     one metal oxide, metal hydroxide and/or metal oxide hydrate applied     in layer B, in relation to the metal ion, is different than the     metal ion(s) of the metal oxides, metal hydroxides and/or metal     oxide hydrates of layer A and layer C, -   (iii) calcining the product obtained in step (ii) at a temperature     from a range from 400° C. to 1000° C. to obtain the red effect     pigment.

The object is alternatively achieved by provision of a process for producing the red effect pigment of the invention, wherein the process comprises the following steps:

-   (i) sequentially applying two uncalcined layers B and C each     composed of or comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate to a calcined, singly or multiply coated     nonmetallic substrate, where the metal ion of layer B comprises or     is at least one metal ion selected from the group of metals     consisting of Ti, Sn and Zr, the metal ion of layer C comprises or     is at least one metal ion selected from the group of metals     consisting of Fe, Ti and Zr, at least one metal ion in the layer     that directly adjoins layer B in substrate direction and/or the     layer C comprises or is an iron ion, layers B and C are arranged     directly one on top of another, and wherein the at least one metal     oxide, metal hydroxide and/or metal oxide hydrate applied in layer B     is different in relation to the metal ion than the metal ion(s) of     the metal oxide, metal hydroxide and/or metal oxide hydrate of layer     C and of the layer that directly adjoins layer B in substrate     direction, where the metal ion(s) of the metal oxide, metal     hydroxide and/or metal oxide hydrate of the layer that directly     adjoins layer B in substrate direction comprises or is at least one     metal ion selected from the group of metals consisting of Fe, Ti and     Zr, -   (ii) calcining the product obtained in step (i) at a temperature     from a range from 400° C. to 1000° C. to obtain the red effect     pigment.

The invention further provides for the use of the red effect pigment of the invention in cosmetic formulations, plastics, films, textiles, ceramic materials, glasses, paints, printing inks, writing inks, varnishes, powder coatings and/or as laser marking additive.

The object underlying the invention is additionally achieved by provision of an article, wherein the article includes at least one red effect pigment of the invention.

What is meant by the expression “a metal ion” or “an iron ion” in accordance with the invention is not one single metal ion or iron ion, but a multitude of metal ions or iron ions.

The nonmetallic substrates in platelet form that are to be coated may be selected from the group consisting of natural mica platelets, synthetic mica platelets, iron mica platelets, glass platelets, iron oxide platelets, SiO₂ platelets, Al₂O₃ platelets, kaolin platelets, talc platelets and bismuth oxychloride platelets. According to the invention, the red effect pigments may also be based on mixtures of the above-specified nonmetallic substrates in platelet form. The aforementioned nonmetallic substrates in platelet form may also include one or more layers composed of or comprising at least one metal oxide, metal hydroxide and/or metal oxide hydrate of high and/or low refractive index. For instance, the substrates used may thus also be singly or multiply coated pearlescent pigments or interference pigments. In a preferred embodiment, the substrates to be used in accordance with the invention are uncoated nonmetallic substrates in platelet form.

The nonmetallic substrates in platelet form are preferably selected from the group consisting of natural mica platelets, synthetic mica platelets, glass platelets, SiO₂ platelets, Al₂O₃ platelets and mixtures thereof. The nonmetallic substrates in platelet form are more preferably selected from the group consisting of natural mica platelets, synthetic mica platelets, glass platelets and mixtures thereof. Very particularly preferred nonmetallic substrates in platelet form are synthetic mica platelets and/or glass platelets and mixtures thereof. Especially glass platelets are preferred as nonmetallic substrate in platelet form.

The glass platelets usable as substrate may, with regard to their composition, consist of silicate glass, such as soda-lime glass, lead crystal glass, E glass, A glass, C glass, ECR glass, Duran glass, window glass, laboratory glass, aluminosilicate glass or borosilicate glass. Preferably, the glass platelets have a composition corresponding to the teaching, especially corresponding to the main claim, of EP 1 980 594 B1, more preferably corresponding to the teaching, especially according to the respective main claims, of EP 1 829 833 B1 or EP 2 042 474 B1. The glass platelets usable as substrate are preferably produced by the process described in EP 289 240 B1.

In a further embodiment, the glass platelets can be colored in a controlled manner in the course of their production by the addition of at least one inorganic colorant. Suitable colorants are those that do not break down at the particular melting temperature of the glass composition. The proportion of colorant here is preferably within a range from 0.1% by weight to 50% by weight in total, more preferably within a range from 1% by weight to 35% by weight in total and most preferably within a range from 5% by weight to 25% by weight in total, based in each case on the total weight of the glass composition. Suitable colorants are especially elemental noble metals, such as Au, Pd or Pt, the cations or complex anions of the elements Cu, Cr, Mn, Fe, Ti and/or Co, and mixtures of the colorants listed above.

In a further embodiment, the refractive index of the glass platelets usable as substrate is within a range from 1.45 to 1.80, preferably within a range from 1.50 to 1.70.

In a further embodiment, the substrates in platelet form, especially glass platelets, may be ensheathed by a layer comprising or consisting of silicon oxide, silicon hydroxide and/or silicon oxide hydrate. For example, the aforementioned coating, in the case of use of glass platelets, can protect the glass surface from chemical alteration, such as swelling, leaching of glass constituents or dissolution in aggressive acidic coverage solutions.

The synthetic mica platelets usable as substrate may have a composition according to the main claim of CN 102718229 A or according to the main claim of US 2014/0251184 A1. They may additionally be produced according to the details in EP 0 723 997 A1, page 3 to page 4.

The synthetic mica platelets usable as substrate are preferably fluorphlogopite of the formula KMg₃AlSi₃O₁₀F₂, KMg₂½(Si₄O₁₀)F₂ or NaMg₂½(Si₄O₁₀) F₂, especially fluorphlogopite of the formula KMg₃AlSi₃O₁₀F₂, which, according to x-ray fluorescence analysis (XRF), preferably has the constituents specified in table 1 as the respective metal oxide within the ranges listed therein.

TABLE 1 Preferred compositions of synthetic mica platelets according to XRF Composition of synthetic mica platelets, figures in % by weight, based in each case on the total weight of the synthetic mica platelets SiO₂ 38 to 46 Al₂O₃ 10 to 14 K₂O  9 to 13 Fe₂O₃ 0.01 to 0.25 MgO 26 to 34 MnO   0 to 0.05 Na₂O  0 to 13

The mean thickness of the nonmetallic substrates in platelet form that are to be coated is preferably within a range from 50 nm to 5000 nm, more preferably within a range from 60 nm to 3000 nm and most preferably within a range from 70 nm to 2000 nm. The mean thickness is understood in accordance with the invention to mean the arithmetic mean, unless stated otherwise.

In one embodiment, the mean thickness for glass platelets as the nonmetallic substrate in platelet form that is to be coated is within a range from 750 nm to 1500 nm, preferably within a range from 850 nm to 1400 nm and more preferably within a range from 900 nm to 1300 nm.

Thinner substrates in platelet form lead to a lower total thickness of the red effect pigments of the invention. Thus, likewise preferred as nonmetallic substrate in platelet form are glass platelets wherein the mean thickness is within a range from 50 nm to 700 nm, further preferably within a range from 101 nm to 600 nm, more preferably within a range from 160 nm to 500 nm and most preferably within a range from 200 nm to 400 nm.

In a further embodiment, the mean thickness of the natural or synthetic mica platelets as the nonmetallic substrate in platelet form that is to be coated is preferably within a range from 80 nm to 1300 nm, further preferably within a range from 90 nm to 1000 nm, more preferably within a range from 99 nm to 800 nm and most preferably within a range from 200 nm to 600 nm.

If nonmetallic substrates in platelet form are coated below a mean thickness of 50 nm with metal oxides of high refractive index, for example, extremely fracture-sensitive pigments are obtained, which can break up even on incorporation into the respective application medium, which in turn results in significant lowering of the gloss.

Above a mean substrate thickness of 5000 nm, the pigments can become too thick overall. This is associated with a poorer specific hiding capacity, meaning that the area covered per unit weight of red effect pigment of the invention is lower. Moreover, such thick pigments have a lower degree of plane-parallel orientation to the substrate in the application medium. Poorer orientation in turn results in reduced gloss. With regard to tactile properties too, excessively thick effect pigments can be disadvantageous overall in an application.

In one embodiment, the relative standard deviation in the thickness distribution of the nonmetallic substrates in platelet form is 15% to 100%, preferably 17% to 70%, more preferably 19% to 61% and most preferably 21% to 41%. The relative standard deviation in [%] is the quotient of calculated standard deviation and mean thickness.

The mean thickness of the nonmetallic substrate in platelet form is determined, using a cured lacquer film in which the red effect pigments of the invention are aligned essentially plane-parallel to the substrate, according to the details below in section IIj “Determination of the mean thickness of the nonmetallic substrates in platelet form, the mean layer thickness of layers 2 and 3, the mean layer thickness of the overall coating, the mean height h_(a) of the spacer layer and the mean height h_(H) of the cavities”. For this purpose, a transverse section of the cured lacquer film is examined under a scanning electron microscope (SEM), wherein the thickness of the nonmetallic substrate in platelet form is determined for at least 100 effect pigments and statistically averaged. According to the invention, the term “mean” always means the arithmetic mean, unless stated otherwise.

The scanning electron micrographs were obtained using transverse sections of the red effect pigments of the invention with the Supra 35 scanning electron microscope (from Zeiss).

The red effect pigments of the invention optionally comprise a layer 1 comprising or consisting of tin oxide, tin hydroxide and/or tin oxide hydrate. Layer 1 may optionally be present at least partly as a mixed layer with a layer directly adjoining layer 1, for example layer 2.

Layers 2 and 3 of the red effect pigments of the invention, after calcination, are preferably each a layer of high refractive index, wherein the refractive index is preferably n>1.8, more preferably n≧1.9 and most preferably n≧2.1. According to the invention, the selection of the at least two different metal ions, where at least one of the two different metal ions is iron ions, in layers 2 and 3 is made such that the metal oxide(s), metal hydroxide(s) and/or metal oxide hydrate(s) that form therefrom in layers 2 and/or 3 preferably each has or have an averaged refractive index of n>1.8.

The at least one metal oxide, metal hydroxide and/or metal oxide hydrate of layers 2 and 3 comprises at least two different metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr, where one of the two different metal ions is an iron ion. According to the invention, the selection of the at least two different metal ions and the proportion of iron ions should be made here such that the resulting effect pigments are red in color. What is meant by “red effect pigments” in the context of this invention is that their hue angle h*₁₅ in the CIE LCh color space is within a range from 320° to 360° and 0° to 60°, further preferably within a range from 330° to 360° and 0° to 55°, more preferably within a range from 335° to 360° and 0° to 45° and most preferably within a range from 340° to 360° and 0° to 400° (FIG. 9). Preferably, the chroma C*₁₅ within the aforementioned hue angle ranges is >28, more preferably >39 and most preferably >46.

The hue angle h*₁₅ and the chroma C*₁₅ are determined here using lacquer applications to black/white hiding charts (Byko-Chart 2853, from Byk-Gardner) according to the details which follow in section IIb “Angle-dependent color measurements”. To this end, the effect pigments of the invention are stirred into a conventional nitrocellulose lacquer (Erco 2615e bronze mixing lacquer colorless; from Maeder Plastiklack AG) at a pigmentation level of 6% by weight, based on the total weight of the wet lacquer, and applied to black/white hiding charts in a wet film thickness of 40 μm, 76 μm or 100 μm with a spiral applicator, subsequently dried at room temperature and analyzed with the BYK-mac multi-angle colorimeter from Byk-Gardner.

TABLE 2 Wet film thickness as a function of the D₅₀ of the red effect pigments Spiral D₅₀ applicator <40 μm 40 μm 40 μm-85 μm 76 μm >85 μm 100 μm 

The CIE LCh color space is the CIELab color space, wherein the cylinder coordinates C* (chroma, relative color saturation, distance from the L axis) and h* (hue angle, angle of the hue in the CIELab color circle) are reported rather than the Cartesian coordinates a*, b* (FIG. 8).

The hiding quotient D_(q), defined as

${D_{q} = \frac{L_{black}^{*110}}{L_{white}^{*110}}},$

of the red effect pigments of the invention is preferably ≧0.41, preferably ≧0.45, more preferably ≧0.50 and most preferably ≧0.55. The hiding quotient is determined here using lacquer applications, on black/white hiding charts (Byko-Chart 2853, from Byk-Gardner), of a nitrocellulose lacquer (Erco 2615e bronze mixing lacquer colorless; from Maeder Plastiklack AG) which has been admixed with 6% by weight of the particular effect pigment of the invention, according to the details which follow in section IIc “Comparison of hiding”. L*¹¹⁰ _(black) and L*¹¹⁰ _(white) here are the brightness values measured at a measurement angle of 110° on black and white backgrounds of the black/white hiding charts, preferably with the BYK-mac multi-angle colorimeter from Byk-Gardner.

What is meant by “at least two different metal ions” in accordance with the invention is that at least two metal ions of different elements are present, for example titanium and iron ions, or iron and tin ions, or iron and zirconium ions etc. The various metal ions may be present in layer 2 and/or layer 3 of the red effect pigment of the invention in a mixture of metal oxides and/or metal hydroxides and/or metal oxide hydrates and/or else in mixed oxides and/or mixed hydroxides and/or mixed oxide hydrates. Layer 2 and/or layer 3 may comprise or consist of this mixture of metal oxides and/or metal hydroxides and/or metal oxide hydrates and/or mixed oxides and/or mixed hydroxides and/or mixed oxide hydrates.

The proportion of iron oxide, iron hydroxide and/or iron oxide hydrate in the red effect pigment of the invention is preferably within a range from 17% by weight to 90% by weight, more preferably within a range from 20% by weight to 86% by weight and most preferably within a range from 36% by weight to 78% by weight, determined in each case by means of XRF, calculated in each case as elemental iron and based in each case on the total weight of the red effect pigment of the invention.

According to the invention, the proportion of metal oxide, metal hydroxide and/or metal oxide hydrate in the red effect pigment, where the at least one metal ion comprises or is a metal ion from the group of metals consisting of Sn, Ti and Zr, is preferably within a range from 0.5% by weight in total to 25% by weight in total, further preferably within a range from 0.9% by weight in total to 21% by weight in total, more preferably within a range from 1.5% by weight in total to 16% by weight in total and most preferably within a range from 2.0% by weight in total to 12% by weight in total, and the proportion of iron oxide, iron hydroxide and/or iron oxide hydrate is preferably within a range from 25% by weight to 90% by weight, further preferably within a range from 28% by weight to 84% by weight, more preferably within a range from 30% by weight to 76% by weight and most preferably within a range from 32% by weight to 71% by weight, determined in each case by means of XRF, calculated in each case as the metal oxide, based in each case on the total weight of the red effect pigment.

In one embodiment, the red effect pigments of the invention do not comprise any tin oxide, tin hydroxide and/or tin oxide hydrate in either of layers 2 and 3. In this case, the proportion of tin oxide, tin hydroxide and/or tin oxide hydrate in the red effect pigment is preferably within a range from 0.04% by weight to 1.5% by weight, more preferably within a range from 0.09% by weight to 1.3% by weight and most preferably within a range from 0.1% by weight to 0.9% by weight, determined in each case by means of XRF as tin dioxide and based in each case on the total weight of the red effect pigment of the invention.

In a preferred embodiment, at least one of layers 2 and 3 comprises metal oxides, metal hydroxides and/or metal oxide hydrates, where the metal ions of the metal oxides, metal hydroxides and/or metal oxide hydrates comprise or are the metals Ti and Fe, where the weight ratio of Ti to Fe, determined in each case by means of XRF and calculated in each case as the elemental metal, is preferably within a range of <8, further preferably within a range of <5, more preferably within a range of <2 and most preferably within a range from <1, and where the proportion of Fe, determined by means of XRF and calculated as the elemental metal, is preferably within a range from 18% by weight to 85% by weight, based on the total weight of the red effect pigment of the invention.

In a particularly preferred embodiment, at least one of layers 2 and 3 comprises metal oxides, metal hydroxides and/or metal oxide hydrates, where the metal ions of the metal oxides, metal hydroxides and/or metal oxide hydrates comprise or are the metals Sn and Fe, where the weight ratio of Sn to Fe, determined in each case by means of XRF and calculated in each case as the elemental metal, is preferably within a range of <5, further preferably within a range of <2, more preferably within a range of <1 and most preferably within a range from <0.5, and where the proportion of Fe, determined by means of XRF and calculated as the elemental metal, is preferably at within a range from 19% by weight to 83% by weight, based on the total weight of the red effect pigment of the invention.

In a further particularly preferred embodiment, at least one of layers 2 and 3 comprises metal oxides, metal hydroxides and/or metal oxide hydrates, where the metal ions of the metal oxides, metal hydroxides and/or metal oxide hydrates comprise or are the metals Zr and Fe, where the weight ratio of Zr to Fe, determined in each case by means of XRF and calculated in each case as the elemental metal, is preferably within a range of <0.5, further preferably within a range of <0.2, more preferably within a range of <0.12 and most preferably within a range from <0.09, and where the proportion of Fe, determined by means of XRF and calculated as the elemental metal, is preferably within a range from 19% by weight to 61% by weight, based on the total weight of the red effect pigment of the invention.

If the at least one metal oxide, metal hydroxide and/or metal oxide hydrate from layers 2 and 3 comprises at least two different metal ions, where one of the two different metal ions is an iron ion, the two different metal ions are preferably either in homogeneous distribution in layers 2 and/or 3 or form a gradient therein. In exceptional cases, the at least two different metal ions may also be present in inhomogeneous distribution in layers 2 and/or 3.

In one embodiment, one of the two layers 2 and 3 comprises only one kind of metal ion, preferably selected from the group of metals consisting of Fe, Sn, Ti and Zr, further preferably consisting of Fe, Sn and Zr. Correspondingly, the respective other layer of the two layers 3 and 2 has at least two different metal ions, preferably selected from the group of metals consisting of Fe, Sn, Ti and Zr, further preferably consisting of Fe, Sn and Zr.

In a preferred embodiment, both layer 2 and layer 3 comprise at least one metal oxide, metal hydroxide and/or metal oxide hydrate composed of comprising at least two different metal ions, preferably selected from the group of metals consisting of Fe, Sn, Ti and Zr, further preferably consisting of Ti, Sn and Fe, where at least one of the two different metal ions in layer 2 and layer 3 is an iron ion.

In a preferred embodiment, the layers 2 and 3 interrupted by the spacer layer are identical in respect of the particular composition.

The metal oxide, metal hydroxide and/or metal oxide hydrate contents of the red effect pigments of the invention are determined as the respective metal oxide by means of x-ray fluorescence analysis (XRF) and can be calculated as the respective elemental metal. For this purpose, the red effect pigment is incorporated into a lithium tetraborate glass tablet, fixed in solid sample measuring cups and analyzed therefrom. The measuring instrument used is the Advantix ARL system from Thermo Scientific.

The mean layer thickness of layer 1 is preferably less than 10 nm, more preferably less than 5 nm and most preferably less than 3 nm, with layer 1 completely ensheathing or incompletely ensheathing the nonmetallic substrate in platelet form or an optionally present coating.

The mean layer thickness of each of layers 2 and 3 of the red effect pigments of the invention is preferably within a range from 30 nm to 300 nm, further preferably within a range from 35 nm to 290 nm, further preferably within a range from 40 nm to 270 nm, more preferably within a range from 40 nm to 275 nm and most preferably within a range from 45 nm to 210 nm.

In one embodiment, the mean layer thickness of layers 2 and 3 is virtually the same.

What is meant by “virtually the same mean layer thickness” in accordance with the invention is that the quotient of the mean layer thickness of layer 2 and the mean layer thickness of layer 3 is preferably within a range from 0.3 to 2.5, further preferably within a range from 0.4 to 2.1, more preferably within a range from 0.5 to 1.9 and most preferably within a range from 0.4 to 1.6.

In a further embodiment, in the case of a different physical composition of layers 2 and 3, the respective optical layer thickness thereof is virtually the same, where the optical layer thickness of layers 2 and 3 may or may not follow the known lambda/4 rule. The optical layer thickness is defined as the product of refractive index and mean layer thickness of the respective layer.

The mean layer thickness of the overall coating of the red effect pigments of the invention is preferably 600 nm. The mean layer thickness of the overall coating is preferably within a range from 45 nm to 550 nm, more preferably within a range from 65 nm to 480 nm and most preferably within a range from 75 nm to 350 nm.

“Overall coating” is understood to mean the complete coating which proceeds from the substrate surface and extends perpendicularly therefrom in one direction.

In one embodiment, the relative standard deviation of the layer thickness distribution of layers 2 and 3 is 2% to 74%, preferably 3% to 63%, more preferably 4% to 57% and most preferably 5% to 49%, and the relative standard deviation of the layer thickness distribution of the overall coating is 0.3% to 31%, preferably 1% to 27%, more preferably 1.2% to 24% and most preferably 1.9% to 22%. The relative standard deviation in [%] is the quotient of calculated standard deviation and mean thickness.

The spacer layer between layers 2 and 3 is preferably arranged essentially parallel to the surface of the nonmetallic substrate in platelet form. What is understood by “essentially parallel” in the context of this invention is that, in a scanning electron micrograph of a transverse section, a regression line drawn through a spacer layer, in relation to a regression line drawn through the surface of the nonmetallic substrate in platelet form, has a slope of preferably close to 0.

The position of the spacer layer within the overall coating may vary. If, for example, the mean layer thicknesses of layers 2 and 3 are virtually identical, the spacer layer, in relation to the overall coating, preferably composed of optional layer 1 and layers 2 and 3, is in about the middle of the overall coating, since the optional layer 1 is preferably extremely thin, more preferably just a few atom layers thick. The spacer layer is preferably arranged between the first sixth and the sixth sixth of the overall coating in relation to the overall coating. The first sixth here refers to the proportion facing the nonmetallic substrate in platelet form, and the sixth sixth to the proportion of the overall coating remote from the nonmetallic substrate in platelet form (FIG. 7).

The spacer layer formed between layers 2 and 3 preferably has connections, which can also be referred to as spacers, which on the one hand connect the layers adjoining on either side of the spacer layer and on the other hand keep them spaced apart. As apparent from scanning electron micrographs of transverse sections, these connections or spacers, for example in the form of bars or columns, may be arranged at an angle of about 90°, for example of 80° to 100°, to the surface of the nonmetallic substrate in platelet form. However, they may also assume any other angle between 5° and 175°. Preferably, the spacers, especially bars, preferably the longitudinal axes of the spacers, preferably bars, are arranged at an angle from a range from 15° to 150° and more preferably at an angle from a range from 35° to 135°, in each case to the surface of the nonmetallic substrate in platelet form. In the determination of the angle, the substrate plane forms the first limb. One of the outsides of the bar in question in each case forms the second limb. The angle formed is determined proceeding from the angle vertex of the two limbs, with 0° being assumed to lie to the left and 180° to the right in the substrate plane in the top view of the scanning electron micrographs of transverse sections.

The connections or spacers may assume various geometric forms and are preferably distributed homogeneously over the entire spacer layer. For example, the connections or spacers may take the form of meshes, grids, ladders, sponges or honeycombs. It may also be possible to identify some structural elements similar to those in a photonic or inverse photonic crystal, as known, for example, from EP 2 371 908 A2, EP 1 546 063 A1 or EP 1 121 334 A1.

The connections or spacers comprise at least one metal oxide, metal hydroxide and/or metal oxide hydrate. In a preferred embodiment, the connections or spacers comprise an identical physical composition to the layers on either side of the spacer layer. It is also alternatively possible for a gradient between various metal oxides, metal hydroxides and/or metal oxide hydrates to be formed within the connections or spacers.

In a preferred embodiment, the connections or spacers comprise a metal oxide, metal hydroxide and/or metal oxide hydrate, where the metal ions of the metal oxides, metal hydroxides and/or metal oxide hydrates comprise or are at least two metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr, further preferably from the group consisting of Fe, Ti and Sn, and more preferably from the group consisting of Fe and Sn, and at least one of the two different metal ions is an iron ion.

The inventors assume that the connections or spacers can also bring about mechanical stabilization of the adjoining layers and hence of the red effect pigment of the invention. Probably because of the number of connections or spacers, the different angles and geometric forms that the connections or spacers can assume within the spacer layer, and the distribution thereof in a preferably homogeneous manner over the full area of the spacer layer, a mechanically very stable effect pigment is formed. The adhesion between the overall coating and the nonmetallic substrate in platelet form is very good in the red effect pigments of the invention. Even extreme shear conditions as occur in what is called the Waring blender test are withstood by the red effect pigments of the invention without detectable damage. The procedure of the Waring blender test is described hereinafter in section IIf “Waring blender test”.

As well as their surprisingly good mechanical stability, the red effect pigments of the invention have excellent chemical stability, as elucidated in the details below in section IIg “Determination of chemical stability”.

The spacer layer of the red effect pigments of the invention preferably has a mean height h_(a) from a range from 3 nm to 120 nm, further preferably from a range from 6 nm to 99 mm, further preferably from a range from 14 nm to 76 nm, further preferably from a range from 21 nm to 69 nm, more preferably from a range from 22 nm to 62 nm and most preferably from a range from 26 nm to 56 nm (FIG. 6).

To determine the mean height h_(a) of the spacer layer, the mean layer thickness of layers 2 and 3 and the mean layer thickness of the overall coating, scanning electron micrographs of transverse sections are used to establish the upper and lower substrate surfaces as baselines in each case. What is meant by the upper and lower substrate surfaces in the scanning electron micrograph of the transverse section is the longer side of the nonmetallic substrate in platelet form in each case. The baseline is drawn onto the scanning electron micrograph of the transverse section along the surface of the nonmetallic substrate in platelet form. The scanning electron micrographs of transverse sections were analyzed with the aid of the AxioVision 4.6.3 image processing software (from Zeiss).

A sufficient number of parallel lines are drawn at 50 nm intervals at a 90° angle from these two baselines as to place a grid over the effect pigment shown in the scanning electron micrograph of the transverse section (FIG. 4). The magnification of the scanning electron micrograph of the transverse section is preferably at least 50 000-fold, based on Polaroid 545 (4″×5″). Proceeding from the respective baseline of the nonmetallic substrate in platelet form, in the direction of the respective outer layer 3 or the respective outermost layer, the points of intersection between the parallel lines arranged at right angles to the respective baseline with the respective interfaces of the optional layer 1 with layer 2, of layer 2 with the spacer layer, of the spacer layer with layer 3, and of layer 3 with the environment or with any further layer applied were analyzed manually. It may be the case here that one of the lines drawn at 50 nm intervals occurs directly above a connection point or a spacer. In this case, only the respective point of intersection of the line at the interface of layer 3 with the environment or with any further layer applied is recorded.

These measurements give rise to the layer thicknesses of layers 2 and 3, the layer thickness of the overall coating, the layer thickness of further layers optionally present, and the height h_(a) of the spacer layer by formation of differences. The layer thickness of layer 2 is calculated from the difference between the respective measured points of intersection at the respective interfaces of layer 2 with the spacer layer and of either optional layer 1 with layer 2 or the baseline with layer 2 if the nonmetallic substrate in platelet form has not been covered with further layers beforehand. The layer thickness of layer 3 is calculated from the difference between the respective measured points of intersection of layer 3 with the environment or any further layer applied and of the spacer layer with layer 3. The layer thickness of the overall coating is calculated from the difference between the respective points of intersection of layer 3 with the environment or any further layer applied with the environment and the respective baseline. The height h_(a) of the spacer layer is calculated from the difference between the respective measured points of intersection of spacer layer with layer 3 and layer 2 with the spacer layer. The layer thicknesses of any further layers applied can be determined analogously and should be taken into account correspondingly in forming the differences.

The individual values of the layer thicknesses and the height h_(a) that have been determined in this way are used to form the respective arithmetic means in order to determine the above-specified values for the mean layer thicknesses and the mean height h_(a). To be statistically meaningful, the above-described measurements are conducted on at least 100 of the parallel lines arranged at right angles to the baselines.

The height h_(ma) refers to the midpoint of the spacer layer. It is calculated as the sum total of the layer thickness of the optional layer 1 and of layer 2 and half the height h_(a) of the spacer layer. The relative height h_(Rma) of the midpoint of the spacer layer is formed from the ratio of h_(ma) and the layer thickness of the overall coating. The standard deviation of the relative height σh_(Rma) is preferably within a range from 0.2% to 18%, further preferably within a range from 0.3% to 15%, more preferably within a range from 0.4% to 11% and most preferably within a range from 0.5% to 8%. The standard deviation of the relative height σh_(Rma) is a measure of the extent to which the spacer layer is in a defined position parallel to the surface of the nonmetallic substrate in platelet form over the entire coating.

If the red effect pigments of the invention have at least one further spacer layer, the height(s) h_(ma) thereof and the relative height(s) of the midpoint of the at least one further spacer layer h_(Rma) thereof are also ascertained via the above-described method using scanning electron micrographs of transverse sections. The above-specified values for standard deviation of the relative height σh_(Rma) apply correspondingly to further spacer layers.

The person skilled in the art is aware that pearlescent pigments coated with titanium dioxide, for example, have pores in the coating that are statistically distributed over the entire coating (FIG. 5). These pearlescent pigments do not have a spacer layer. The spacer layer and the cavities present within the spacer layer in the red effect pigments of the invention, by contrast, are not statistically distributed over the entire coating, but are arranged parallel to the surface of the nonmetallic substrate in platelet form over the entire coating.

The distances of the midpoints of the statistically distributed pores from the substrate surface were likewise determined by means of scanning electron micrographs of transverse sections by the method described above. For this purpose, a sufficient number of parallel lines were drawn at 50 nm intervals at a 90° angle with respect to the upper and lower baselines corresponding to the two surfaces of the substrate in platelet form that a grid has been placed over the pearlescent pigment without a spacer layer shown in the scanning electron micrograph of a transverse section. If one of the parallel lines occurred above one or more pores, the height(s) thereof, the pore midpoint(s) thereof and the distance of the pore midpoint(s) from the substrate surface were determined. The statistical distribution of the pore midpoints can likewise be used to determine a standard deviation.

The standard deviation of the distances of the midpoints of the statistically distributed pores from the substrate surface is >20% in pearlescent pigments from the prior art, i.e. in the case of pearlescent pigments without a spacer layer. The standard deviation of the distances of the midpoints of the statistically distributed pores from the substrate surface is thus distinctly different in terms of its value from the standard deviation of the relative height of the midpoint of the spacer layer of the red effect pigments of the invention.

It is thus possible to compare the standard deviation of the distances of the pore midpoints from the substrate surface of pearlescent pigments without a spacer layer with the standard deviation of the relative height of the midpoint of the spacer layer of red effect pigments of the invention.

In addition, with the aid of the above-described lines drawn at 50 nm intervals in a scanning electron micrograph, the number of connections or spacers per micrometer and the network density, defined as the number of connections or spacers per number of lines in %, is determined.

If the red effect pigments of the invention have more than one spacer layer within the overall coating, the method just described for measuring the individual layers and the spacer layers is applied correspondingly.

In one embodiment, the standard deviation of the relative height of the spacer layer σh_(Rma) is <25%, preferably within a range from 0.5% to 23%, more preferably 1% to 21% and most preferably 13% to 60%.

In a preferred embodiment, the red effect pigments of the invention, within the at least one spacer layer, have a number of connections or spacers per micrometer from a range from 0 to 11, further preferably from a range from 0 to 9, more preferably from a range from 1 to 7 and most preferably from a range from 1 to 3.

In a preferred embodiment, the red effect pigments of the invention, within the at least one spacer layer, have a network density, defined as the number of connections or spacers per number of lines in percent, of <85%, preferably from a range from 1% to 75%, more preferably from a range from 1% to 63% and most preferably from a range from 1% to 49%.

Above a network density of 85%, in the context of this invention, reference is no longer made to a spacer layer since the high proportion of connections or spacers then leads to a very substantially continuous coating.

In a further preferred embodiment, the red effect pigments of the invention comprise at least one spacer layer arranged essentially parallel to the surface of the nonmetallic substrate in platelet form, where the at least one spacer layer in each case has a mean height h_(a) from a range from 5 nm to 115 nm, more preferably from a range from 8 nm to 76 nm and most preferably from a range from 16 nm to 67 nm.

In a particularly preferred embodiment, the red effect pigments of the invention have at least one spacer layer of mean height h_(a) from a range from 5 nm to 112 nm, preferably from a range from 9 nm to 96 nm and most preferably from a range from 15 nm to 76 nm, where the number of connections or spacers per micrometer within the at least one spacer layer is selected from a range from 0 to 8, preferably from a range from 0 to 6, more preferably from a range from 0.1 to 5 and most preferably from a range from 0.3 to 4.

The spacer layer comprises cavities as well as the above-described connections or spacers. These cavities are spatially bounded by layers 2 and 3 and the connections or spacers. The cavities of further spacer layers that are optionally present have analogous delimitations.

Energy-dispersive x-ray microanalysis (EDX analysis) of these cavities does not permit any conclusion as to whether the material is solid or liquid, and so the inventors are assuming, with the methods of analysis available at present, that the cavities within the spacer layer comprise a gas, probably air. The connections or spacers, by contrast, comprise at least one metal oxide, metal hydroxide and/or metal oxide hydrate, as detailed above.

The cavities within the spacer layer of the red effect pigments of the invention may assume a mean height h_(H) from a range from 2 nm to 119 nm, preferably from a range from 6 nm to 105 nm, more preferably from a range from 11 nm to 85 nm and most preferably from a range from 18 nm to 53 nm. The height h_(H) is understood to mean the greatest difference between the uppermost and lowermost cavity boundaries. It is determined by the method described above for the height h_(a), by drawing parallel lines at 50 nm intervals at a 90° angle to the surface of the nonmetallic substrate in platelet form in scanning electron micrographs of transverse sections. The difference of the two points of intersection of these lines with the upper and lower cavity boundaries is the height h_(H). Here too, to be statistically meaningful, the above-described measurements are conducted on at least 100 lines. Therefore, the mean height h_(a) is a maximum value for the mean height h_(H). Accordingly, it is also possible for a plurality of cavities to be present one above another within the spacer layer.

The mean height of the spacer layer h_(a) and the mean height of the cavities h_(H) are determined, using a cured lacquer film in which the red effect pigments of the invention are aligned essentially plane-parallel to the substrate, according to the details given in section IIj “Determination of the mean thickness of the nonmetallic substrates in platelet form, the mean layer thickness of layers 2 and 3, the mean layer thickness of the overall coating, the mean height h_(a) of the spacer layer and the mean height h_(H) of the cavities”. For this purpose, a transverse section of the cured lacquer film is examined under a scanning electron microscope (SEM), as described above for h_(a). As an alternative to these transverse sections, the red effect pigments of the invention can be cut by means of the FIB method (FIB=focused ion beam). For this purpose, a fine beam of highly accelerated ions (for example gallium, xenon, neon or helium) is focused to a point by means of ion optics and guided line by line over the effect pigment surface to be processed. On impact with the effect pigment surface, the ions release most of their energy and destroy the coating at this point, which leads to removal of material line by line. It is also possible using the scanning electron micrographs that have then been recorded, by the method described above, to determine the mean height h_(a), the mean layer thickness of layers 2 and 3 and the mean layer thickness of the overall coating. The mean thickness of the nonmetallic substrate in platelet form can also be determined using scanning electron micrographs of the effect pigments that have been cut by the FIB method.

In a further embodiment, the red effect pigments of the invention comprise, within the spacer layer, distributed over the entire effect pigment and measured using scanning electron micrographs of transverse sections, an area proportion of cavities from a range from 51% to 99%, preferably from a range from 63% to 96%, more preferably from a range from 76% to 95% and most preferably from a range from 84% to 94%, and an area proportion of connections or spacers from a range from 1% to 49%, preferably from a range from 4% to 37%, more preferably from a range from 5% to 24% and most preferably from a range from 6% to 16%.

It is further preferable that the total volume occupied by the connections and spacers in the spacer layer is less than the total volume occupied by the cavities.

Preferably, the total volume occupied by the connections or spacers in the spacer layer is less than 50% by volume, further preferably less than 30% by volume, more preferably less than 20% by volume and most preferably less than 10% by volume of the total volume occupied by the cavities.

In the red effect pigments of the invention, the cavities within the spacer layer, by contrast with the pores of the teaching according to EP 1 422 268 A2, are explicitly desired. According to EP 1 422 268 A2, a coating with low porosity and a minimum number of pores is required to obtain pigments having high chroma and high brilliance. The pigments according to EP 1 422 268 A2 do not have a spacer layer. According to the invention, the cavities that are not distributed randomly within the overall coating but are present essentially parallel to the surface of the nonmetallic substrate in platelet form within the spacer layer do not have any adverse effect on the optical properties of the red effect pigments of the invention. On the contrary, the red effect pigments of the invention, compared to pigments with a single layer coating, feature higher gloss and higher chroma, naturally assuming the same nonmetallic substrate in platelet form, the same particle size and a comparable coating. At the same time, depending on the coating thickness and the type of coating, different interference colors and/or different absorption colors can be obtained.

The higher gloss and the higher chroma can be explained by the maximum difference in refractive index between the spacer layer and the adjoining layers, which, according to Fresnel's law, leads in each case to a maximum reflection of light at these interfaces. For the cavities, the basis used here is the refractive index of air of approximately 1. A light beam hitting the spacer layer is partly reflected at the interfaces thereof, the respective intensity of the reflection according to Fresnel's law being dependent on the difference in refractive index of the adjoining layers from the spacer layer. Since such partial reflection takes place at every single interface, the total reflection also increases with the number of interfaces. In the red effect pigments of the invention, a light beam is thus partly reflected on multiple occasions, the effect of which is much more intense gloss and greater intensity of the interference color compared to conventional, singly coated pigments.

If the cavities are statistically distributed within the overall coating, i.e. not essentially parallel to the nonmetallic substrate in platelet form, there will be a variation in the optical path length within the overall coating. The result of this is that the interference conditions are not adequately fulfilled and hence there will be no amplification or extinction.

The gloss of the red effect pigments of the invention is determined using white/black hiding cards with the aid of a Micro-Tri-Gloss gloss meter from Byk-Gardner, according to the details given hereinafter in section IId “Gloss measurements”. The chroma of the red effect pigments of the invention is likewise determined using white/black hiding cards with the BYK-mac multi-angle colorimeter (from Byk-Gardner), according to the details given hereinafter in section IIb “Angle-dependent color measurements”. Further optical effects, such as sparkles and graininess, are determined according to the details given hereinafter in section Ile “Effect measurements”.

In one embodiment, the red effect pigments of the invention comprise, as well as the above-described layers 1, 2 and 3, further layers of high and/or low refractive index, which may be arranged, viewed from the nonmetallic substrate in platelet form, either below the optional layer 1 or layer 2 and/or above layer 3. These further layers may comprise metal oxides, metal hydroxides, metal oxide hydrates, where the metal ions of the metal oxides, metal hydroxides, metal oxide hydrates comprise or are at least one metal ion selected from the group of metals consisting of Ti, Fe, Sn, Mn, Zr, Ca, Sr, Ba, Ni, Ag, Zn, Cu, Ce, Cr and Co, preferably selected from the group of metals consisting of Ti, Fe, Sn, Zr, Ag, Zn, Cu, Ce, Cr and more preferably selected from the group of metals consisting of Ti, Fe and Sn. Moreover, these further layers may comprise semitransparent metal selected from the group consisting of Ag, Al, Cr, Ni, Au, Pt, Pd, Cu, Zn and Ti, preferably selected from the group consisting of Ag, Au and Cu, the alloys of each and or mixtures thereof.

In one embodiment, each of the layers of the red effect pigments of the invention may be provided with a dopant, where the dopant may comprise metal oxides, metal hydroxides and/or metal oxide hydrates, and the metal ions of the metal oxides, metal hydroxides and/or metal oxide hydrates comprise or are at least one metal ion selected from the group of metals consisting of Ca, Mg, Al, Ce, Zr or Sn, preferably Al, Zr or Sn. The portion of dopant preferably totals 1% by weight, more preferably totals 0.5% by weight and most preferably totals 0.2% by weight, based in each case on the total weight of the red effect pigments.

In a further embodiment, the overall coating of the red effect pigments of the invention may, as well as the spacer layer, comprise at least one further spacer layer also arranged essentially parallel to the surface of the nonmetallic substrate in platelet form between layers 2 and 3. Preferably, the red effect pigments of the invention have not more than four spacer layers within the overall coating, since the optical quality thereof then decreases. According to the invention, even when the red effect pigment of the invention comprises more than one spacer layer, in relation to the overall coating, there is no spacer layer either in the first sixth or in the sixth sixth of the overall coating.

The red effect pigments of the invention may have any median particle size D₅₀. The D₅₀ values of the red effect pigments of the invention are preferably within a range from 3 μm to 350 μm. Preferably, the D₅₀ values of the red effect pigments of the invention are within a range from 4 μm to 211 μm, further preferably within a range from 6 μm to 147 μm, more preferably within a range from 7 μm to 99 μm and most preferably within a range from 8 μm to 56 μm. Exceptionally preferably, the red effect pigments of the invention have a D₅₀ from a range from 3 μm to 15 μm or from a range from 10 μm to 35 μm or from a range from 25 μm to 45 μm or from a range from 30 μm to 65 μm or from a range from 40 μm to 140 μm or from a range from 135 μm to 250 μm.

The D₁₀ values of the red effect pigments of the invention preferably encompass a range from 1 μm to 120 μm. More preferably, the D₁₀ values of the red effect pigments of the invention are within a range from 1 μm to 5 μm or within a range from 5 μm to 25 μm or within a range from 10 μm to 30 μm or within a range from 20 μm to 45 μm or within a range from 25 μm to 65 μm or within a range from 75 μm to 110 μm.

The D₉₀ values of the red effect pigments of the invention preferably encompass a range from 6 μm to 500 μm. More preferably, the D₉₀ values of the red effect pigments of the invention are within a range from 8 μm to 250 μm or within a range from 10 μm to 150 μm or within a range from 40 μm to 70 μm or within a range from 68 μm to 110 μm or within a range from 120 μm to 180 μm or within a range from 400 μm to 490 μm.

The D₁₀, D₅₀ and D₉₀ of the cumulative frequency distribution of the volume-averaged size distribution function, as obtained by laser diffraction methods, indicate that, respectively, 10%, 50% and 90% of the effect pigments analyzed have a volume-averaged diameter less than or equal to the value specified in each case. In this context, the size distribution curve of the red effect pigments of the invention is determined using the Malvern Mastersizer 2000 instrument according to the manufacturer's instructions. The scattered light signals are evaluated by the Fraunhofer theory, which also includes diffraction and absorption characteristics of the particles.

In a preferred embodiment, the red effect pigments of the invention have a span ΔD, defined as ΔD=D₉₀−D₁₀/D₅₀, from a range from 0.7 to 3.0, preferably from a range from 0.7 to 2.3, further preferably from a range from 0.8 to 1.8, more preferably from a range from 0.8 to 1.4 and most preferably from a range from 0.85 to 1.1. The advantages of a narrow size classification in relation to color purity and/or gloss of the resulting effect pigments are described, for example, in EP 2 217 664 A1, EP 2 346 950 A1, EP 2 356 181 A1, EP 2 346 949 A1 or EP 2 367 889 A1.

The red effect pigments of the invention can be produced as follows:

-   -   suspending the nonmetallic substrates in platelet form in water         at a temperature from a range from 50° C. to 100° C.,     -   optionally applying an uncalcined layer comprising or consisting         of tin oxide, tin hydroxide and/or tin oxide hydrate by adding a         water-soluble tin salt with simultaneous addition of a mineral         alkali,     -   sequentially applying three uncalcined layers A, B and C in the         form of metal oxides, metal hydroxides and/or metal oxide         hydrates by sequential addition of three water-soluble metal         salts, in each case with simultaneous addition of mineral         alkali, where the second water-soluble metal salt—for production         of layer B—is different in relation to the metal ion than the         two other water-soluble metal salts for production of layer A         and layer C, each of the respective water-soluble metal salts         for production of layers A and C comprises or is at least one         metal ion selected from the group of metals consisting of Fe, Ti         and Zr, the water-soluble metal salt for production of layer B         comprises or is at least one metal ion selected from the group         of metals consisting of Sn, Ti and Zr, and the water-soluble         metal salt(s) for production of layers A and/or C comprise(s) or         is/are at least one iron ion,     -   separating the coated substrates from the coating solution(s),         and optionally washing and/or optionally drying the coated         substrates,     -   calcining the coated substrates at temperatures from a range         from 400° C. to 1100° C., preferably from a range from 625° C.         to 930° C. and more preferably from a range from 750° C. to         890° C. to obtain the red effect pigments of the invention         comprising at least one spacer layer.

In a preferred embodiment, the red effect pigments of the invention are produced by the above process.

The application, preferably deposition, of the respective metal oxides, metal hydroxides and/or metal oxide hydrates is preferably effected at a constant pH within a range from pH 1.4 to 10.0 depending on the metal salt.

In addition to the at least three sequentially applied, preferably deposited, metal oxides, metal hydroxides and/or metal oxide hydrates, it is of course possible for further metal oxides, metal hydroxides and/or metal oxide hydrates to be applied beforehand and/or subsequently, such that further layers may be arranged beneath or above the layer sequence [optional layer 1/layer 2/spacer layer/layer 3].

In the course of calcining, there is surprisingly diffusion presumably of the metal ions present in the layer B into layer A and/or layer C to form mixed metal oxides and/or mixed metal hydroxides and/or metal oxide hydrates and/or mixtures of metal oxides and/or metal hydroxides and/or metal oxide hydrates in layer A and/or layer C. Because of the diffusion of the metal ions from layer B into layer A and/or layer C in the course of calcining, layers 2 and 3 of the invention and the intermediate spacer layer are formed, with at least one of the two layers 2 and 3 comprising at least two different metal ions. The originally three successively deposited layers A, B and C thus give rise, in the course of calcining, to layers 2 and 3 and the intermediate spacer layer, with at least one of the two layers 2 and 3 comprising at least two different metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr, and at least one of layers 2 and 3 comprising iron ions.

It is assumed that the different mobility of the metal oxides, metal hydroxides and/or metal oxide hydrates with respect to one another in the course of calcining is one of the factors responsible for the formation of the spacer layer. In this context, the mobility of the metal ions present in layer B competes with the mobility of the metal ions present in layers A and/or C, assuming that the metal ions diffuse out of layer B into at least one of the adjoining layers A and/or C and the metal ions diffuse from at least one of layers A and/or C into layer B. The inventors are assuming at present that, if the mobility of the metal ions present in layer B during the calcination is higher than the mobility of the metal ions present in layers A and/or C, is one of the possible explanations for the formation of the spacer layer. Furthermore, it is assumed that a concentration gradient in relation to the metal ions promotes the formation of a spacer layer, i.e. when more mobile metal ions can diffuse out of layer B into one of the adjoining layers A and/or C than in the reverse direction. In summary, it has been found that the formation of a spacer layer is caused by a complex interplay of a wide variety of different further factors, for example entropic and/or enthalpic effects, during the calcination, but these have not yet been conclusively clarified. For the formation of at least one further spacer layer, the above considerations naturally apply correspondingly.

The first and third of the three sequentially applied, preferably deposited, metal oxides, metal hydroxides and/or metal oxide hydrates comprises at least one metal ion selected from the group of metals consisting of Fe, Ti and Zr, where the first and/or third metal oxide, metal hydroxide and/or metal oxide hydrate applied comprises iron ions. The first and third metal oxide, metal hydroxide and/or metal oxide hydrate, after application, respectively produce layer A and layer C. The second of the three sequentially applied, preferably deposited, metal oxides, metal hydroxides and/or metal oxide hydrates produces layer B and comprises at least one metal ion selected from the group of metals consisting of Sn, Ti and Zr, which is different than the metal ions of the metal oxides, metal hydroxides and/or metal oxide hydrates deposited for production of layer A and layer C. In layer A and layer C, the metal oxides, metal hydroxides and/or metal oxide hydrates applied, preferably deposited, may be the same or different in relation to the metal ion(s), where at least one of the layers A and C comprises iron ions.

Alternatively, the red effect pigments of the invention can be produced as follows:

-   -   suspending the calcined, singly or multiply coated nonmetallic         substrates in platelet form in water at a temperature from a         range from 50° C. to 100° C., where the metal ion(s) of the         metal oxide, metal hydroxide and/or metal oxide hydrate of the         layer that directly adjoins the layer B to be applied in         substrate direction comprises or is at least one metal ion         selected from the group of metals consisting of Fe, Ti and Zr,     -   sequentially applying two uncalcined layers B and C in the form         of metal oxides, metal hydroxides and/or metal oxide hydrates by         sequential addition of two water-soluble metal salts, in each         case with simultaneous addition of mineral alkali, where the         first water-soluble metal salt—for production of layer B—is         different in relation to the metal ion than the other         water-soluble metal salt for production of layer C and the layer         that directly adjoins layer B in substrate direction, the         water-soluble metal salt for production of layer B comprises or         is at least one metal ion selected from the group of metals         consisting of Ti, Sn and Zr, the water-soluble metal salt for         production of layer C comprises or is at least one metal ion         selected from the group of metals consisting of Fe, Ti, Zr, at         least one metal ion in the layer that directly adjoins layer B         in substrate direction and/or in layer C comprises or is an iron         ion,     -   separating the coated substrates from the coating solution(s),         and optionally washing and/or optionally drying the coated         substrates,     -   calcining the coated substrates at temperatures from a range         from 400° C. to 1100° C., preferably from a range from 625° C.         to 930° C. and more preferably from a range from 750° C. to         890° C. to obtain the red effect pigments of the invention         comprising at least one spacer layer.

Here too, the application, preferably deposition, of the respective metal oxides, metal hydroxides and/or metal oxide hydrates is preferably effected at a constant pH within a range from pH 1.4 to 10.0 depending on the metal salt.

It is suspected that, in the course of calcining, the metal ions present in the layer B diffuse at least into layer C to form mixed metal oxides and/or mixed metal hydroxides and/or metal oxide hydrates and/or mixtures of metal oxides and/or metal hydroxides and/or metal oxide hydrates in layer C. Because of the diffusion of the metal ions from layer B into layer C, the calcining forms layer 3 of the invention and the spacer layer. The originally two successively deposited layers B and C thus give rise, in the course of calcining, to layer 3 and the spacer layer, with at least layer 3 comprising at least two different metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr. Layer 2 is already present here. Layer 2 refers to the outermost layer of the calcined, singly or multiply coated nonmetallic substrate in platelet form which is used as starting material, where the metal ion(s) of the metal oxide, metal hydroxide and/or metal oxide hydrates of layer 2 comprise(s) at least one metal ion selected from the group of metals consisting of Fe, Ti and Zr, and at least one of layers 2 and 3 comprises iron ions.

The concentration profile (line scan) on the basis of transverse sections in the scanning electron microscope with an energy-dispersive microanalyzer (EDX) shows a significant location-dependent change in the chemical composition of the coating before and after calcination (FIGS. 1 and 2).

FIG. 1 shows a concentration profile of example 1 after coating and drying, but before calcination. With reference to the concentration curves, it can be seen that an Sn maximum (Sn peak) is present in the region of 0.3 μm. This Sn peak shows where the Sn-containing layer applied is present within the coating prior to the calcination. The concentration curve of oxygen, by contrast, has a substantially homogeneous distribution without recognizable minima or maxima.

FIG. 2 likewise shows a concentration profile of example 1 after coating and drying, but after calcination. It is found that the Sn peak present in FIG. 1 has disappeared. The Sn ions have diffused into the surrounding Fe-containing layers. Another feature that should be emphasized is a minimum in the oxygen and iron concentration curves, which indicates the position of the spacer layer.

In a particularly preferred embodiment, the two or three sequentially applied, preferably deposited, metal oxides, metal hydroxides and/or metal oxide hydrates for production of the layers B and C or A, B and C do not comprise any metal ion(s) selected from the group of the metals consisting of Si, Mg and Al.

In the case of sequential application of two uncalcined layers B and C to an already coated and optionally calcined substrate, that layer to which the layer B is applied, in accordance with the invention, comprises a metal oxide, metal hydroxide and/or metal oxide hydrate of high refractive index, in which case the at least one metal ion therein comprises or is a metal ion selected from the group of metals consisting of Fe, Ti and Zr.

In the case of sequential application of three uncalcined layers A, B and C to an already coated and optionally calcined substrate, that layer to which the layer A is applied, in accordance with the invention, may comprises a metal oxide, metal hydroxide and/or metal oxide hydrate of high or low refractive index.

In a preferred embodiment, the red effect pigments of the invention comprise a proportion of iron ions totaling at least 17% by weight, preferably from a range from 19% by weight in total to 76% by weight in total, further preferably from a range from 21% by weight in total to 65% by weight in total, more preferably from a range from 22% by weight in total to 56% by weight in total, more preferably from a range from 23% by weight in total to 47% by weight in total, and a proportion of tin, titanium and zirconium ions totaling 20% by weight, preferably from a range from 0.5% by weight in total to 19% by weight in total, further preferably from a range from 0.8% by weight in total to 14% by weight in total, more preferably from a range from 0.9% by weight in total to 15% by weight in total, most preferably from a range from 1.3% by weight in total to 14% by weight in total, determined in each case by means of XRF, calculated in each case as the elemental metal and based in each case on the total weight of the red effect pigment.

In a particularly preferred embodiment, the red effect pigments of the invention comprise a proportion of iron ions totaling at least 17% by weight, preferably from a range from 19% by weight in total to 76% by weight in total, further preferably from a range from 21% by weight in total to 65% by weight in total, more preferably from a range from 22% by weight in total to 56% by weight in total, more preferably from a range from 23% by weight in total to 47% by weight in total, and simultaneously a proportion of

-   -   i. tin ions totaling 17% by weight, preferably from a range from         0.3% by weight in total to 11% by weight in total, further         preferably from a range from 0.4% by weight in total to 8.5% by         weight in total, more preferably from a range from 0.5% by         weight to 6% by weight in total, most preferably from a range         from 0.2% by weight to 7% by weight in total, or     -   ii. titanium ions totaling 15% by weight, preferably from a         range from 0.1% by weight in total to 14% by weight in total,         further preferably from a range from 0.2% by weight in total to         11% by weight in total, more preferably from a range from 0.5%         by weight in total to 9% by weight in total, most preferably         from a range from 0.8% by weight in total to 5% by weight in         total, or     -   iii. zirconium ions totaling 18% by weight, preferably from a         range from 0.1% by weight in total to 13% by weight in total,         further preferably from a range from 0.5% by weight in total to         12% by weight in total, more preferably from a range from 0.8%         by weight in total to 7% by weight in total, most preferably         from a range from 1.2% by weight in total to 10% by weight in         total, or     -   iv. tin and titanium ions totaling 19% by weight, preferably         from a range from 0.3% by weight in total to 14% by weight in         total, further preferably from a range from 0.5% by weight in         total to 13% by weight in total, more preferably from a range         from 1.1% by weight in total to 9% by weight in total, most         preferably from a range from 1.5% by weight in total to 7% by         weight in total,         determined in each case by means of XRF, calculated in each case         as the elemental metal and based in each case on the total         weight of the red effect pigment.

In one embodiment, the calcination of the red effect pigments of the invention is effected under reducing conditions, preferably in the presence of forming gas (N₂/H₂). A calcination under reducing conditions can be associated with lower brightness values L* than is the case for calcination under air. Depending on the layers A, B and C or B and C applied, it is possible in this embodiment for reduced metal oxides to be formed during the calcination, for example magnetite or ilmenite.

The above remarks are elucidated in detail hereinafter by way of example with reference to various coatings.

If, for example, a water-soluble iron(III) salt, a water-soluble tin(IV) salt and a water-soluble iron(III) salt again are applied successively to a suspension of an optionally coated nonmetallic substrate in platelet form, the calcination, viewed proceeding from the substrate in the SEM transverse section, following the coating which is optionally already present, gives rise to a layer 2 comprising a metal oxide, metal hydroxide and/or metal oxide hydrate, where the metal ions of the metal oxide, metal hydroxide and/or metal oxide hydrate comprise or are from the group consisting of Fe, Ti, Zr, Sn, a spacer layer and a layer 3, where the metal ions of the metal oxide, metal hydroxide and/or metal oxide hydrate of layer 3 comprise or are from the group consisting of Fe, Ti, Zr, Sn. At least one of layers 2 and 3 comprising a metal oxide, metal hydroxide and/or metal oxide hydrate containing iron ions.

If the red effect pigments of the invention, in addition to the at least two or three sequentially applied, preferably deposited, metal oxides, metal hydroxides and/or metal oxide hydrates, include further layers comprising metal oxides, metal hydroxides and/or metal oxide hydrates, it is also possible for further spacer layers to form within the further layers, provided, for example, that the process steps described above for the at least two or three sequentially applied, preferably deposited, metal oxides, metal hydroxides and/or metal oxide hydrates are observed.

The red effect pigments of the invention may optionally be provided with at least one outer protective layer that further increases weathering stability and/or chemical stability. The chemical stability and the condensate water stability were determined according to the details given below in the sections IIg “Determination of chemical stability” and IIi “Condensate water test”.

The optionally present protective layer comprises metal oxides, metal hydroxides and/or metal oxide hydrates wherein the metal ions are selected from the group of metals consisting of Si, Ce, Cr, Al, Zr, Zn and mixtures thereof, preferably from the group of metals Si, Ce, Al, Zr and mixtures thereof. In this context, the proportion of the optionally present protective layer is preferably within a range from 0.1% by weight to 7.0% by weight, more preferably within a range from 0.2% by weight to 5.2% by weight and most preferably within a range from 0.3% by weight to 3.1% by weight, based in each case on the total weight of the red effect pigment of the invention.

The optionally present protective layer may additionally have been surface modified, for example by silanes. The silanes may have no functional bonding group or one or more functional bonding group(s). Silanes having at least one functional bonding group are also referred to hereinafter as organofunctional silanes.

For example, one or more silanes may have been applied to this outermost protective layer. The silanes may be alkylsilanes having branched or unbranched alkyl radicals having 1 to 24 carbon atoms, preferably 6 to 18 carbon atoms.

In a further preferred embodiment, the silane without a functional bonding group is an alkylsilane. The alkylsilane preferably has the formula R_((4-z))Si(X)_(z). In this formula, z is an integer from 1 to 3, R is a substituted or unsubstituted, unbranched or branched alkyl chain having 10 to 22 carbon atoms, and X is a halogen and/or alkoxy group. Preference is given to alkylsilanes having alkyl chains having at least 12 carbon atoms. R may also be bonded to Si in a cyclic manner, in which case z is typically 2.

In a further embodiment, it is also possible to use at least one organofunctional silane which enables a chemical bond to a plastic, a binder of a lacquer or a paint, etc., for surface modification. These groups of the organofunctional silane may also be referred to as coupling groups or functional bonding groups and are preferably selected from the group consisting of hydroxyl, amino, acryloyl, methacryloyl, vinyl, epoxy, isocyanate, cyano and mixtures thereof.

The organofunctional silanes having suitable functional groups that are used with preference as surface modifiers are commercially available and are produced, for example, by Evonik and sold under “Dynasylan” trade name. Further products can be purchased from Momentive (Silquest silanes) or from Wacker, for example standard silanes and α-silanes from the GENIOSIL product group. Examples of these are 3-methacryloyloxypropyltrimethoxysilane (Dynasylan MEMO, Silquest A-174NT), vinyltri(m)ethoxysilane (Dynasylan VTMO and VTEO, Silquest A-151 bzw. A-171), methyltri(m)ethoxysilane (Dynasylan MTMS and MTES), 3-mercaptopropyltrimethoxysilane (Dynasylan MTMO; Silquest A-189), 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, Silquest A-187), tris[3-(trimethoxysilyl)propyl] isocyanurate (Silquest Y-11597), bis[3-(triethoxysilyl)propyl)] tetrasulfide (Silquest A-1289), bis[3-(triethoxysilyl)propyl disulfide (Silquest A-1589), beta-(3,4-epoxycyclohexyl)ethyltrimethoxysi lane (Silquest A-186), bis(triethoxysilyl)ethane (Silquest Y-9805), gamma-isocyanatopropyltrimethoxysilane (Silquest A-Link 35, GENIOSIL GF40), methacryloyloxymethyltri(m)ethoxysilane (GENIOSIL XL 33, XL 36), (methacryloyloxymethyl)(m)ethyldimethoxysilane (GENIOSIL XL 32, XL 34), (isocyanatomethyl)methyldimethoxysilane, (isocyanatomethyl)trimethoxysilane, 3-(triethoxysilyl)propylsuccinic anhydride (GENIOSIL GF 20), (methacryloyloxymethyl)methyldiethoxysilane, 2-acryloyloxyethylmethyldimethoxysilane, 2-methacryloyloxyethyltrimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, 2-acryloyloxyethyltrimethoxysilane, 2-methacryloyloxyethyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltripropoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltriacetoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane (GENIOSIL XL 10), vinyltris(2-methoxyethoxy)silane (GENIOSIL GF 58), vinyltriacetoxysilane or mixtures thereof. Preference is given to using, as organofunctional silanes, 3-methacryloyloxypropyltrimethoxysilane (Dynasylan MEMO, Silquest A-174NT), vinyltri(m)ethoxysilane (Dynasylan VTMO and VTEO, Silquest A-151 and A-171), methyltri(m)ethoxysilane (Dynasylan MTMS and MTES), beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Silquest A-186), bis(triethoxysilyl)ethane (Silquest Y-9805), gamma-isocyanatopropyltrimethoxysilane (Silquest A-Link 35, GENIOSIL GF40), methacryloyloxymethyltri(m)ethoxysilane (GENIOSIL XL 33, XL 36), (methacryloyloxymethyl)(m)ethyldimethoxysilane (GENIOSIL XL 32, XL 34), 3-(triethoxysilyl)propylsuccinic anhydride (GENIOSIL GF 20), vinyltrimethoxysilane (GENIOSIL XL 10) and/or vinyltris(2-methoxyethoxy)silane (GENIOSIL GF 58).

It is also possible to apply other organofunctional silanes to the red effect pigments of the invention. In addition, it is possible to use aqueous prehydrolyzates commercially available, for example, from Degussa. These include aqueous aminosiloxane (Dynasylan Hydrosil 1151), aqueous amino-/alkyl-functional siloxane (Dynasylan Hydrosil 2627 or 2909), aqueous diamino-functional siloxane (Dynasylan Hydrosil 2776), aqueous epoxy-functional siloxane (Dynasylan Hydrosil 2926), amino-/alkyl-functional oligosiloxane (Dynasylan 1146), vinyl-/alkyl-functional oligosiloxane (Dynasylan 6598), oligomeric vinylsilane (Dynasylan 6490) or oligomeric short-chain alkyl-functional silane (Dynasylan 9896).

In a preferred embodiment, the organofunctional silane mixture, as well as at least one silane without a functional bonding group, comprises at least one amino-functional silane. The amino function is a functional group which can enter into one or more chemical interactions with most of the groups present in binders. This may include a covalent bond, for example with isocyanate or carboxylate functions of the binder, or hydrogen bonds such as with OH or COOR functions, or else ionic interactions. An amino function is therefore of very good suitability for the purpose of chemical attachment of the pigment to various kinds of binder.

Preference is given to taking the following compounds for this purpose: 3-aminopropyltrimethoxysilane (Dynasylan AMMO; Silquest A-1110), 3-aminopropyltriethoxysilane (Dynasylan AMEO), [3-(2-aminoethyl)aminopropyl]trimethoxysilane (Dynasylan DAMO, Silquest A-1120), [3-(2-aminoethyl)aminopropyl]triethoxysilane, triamino-functional trimethoxysilane (Silquest A-1130), bis(gamma-trimethoxysilylpropyl)amine (Silquest A-1170), N-ethyl-gamma-aminoisobutyltrimethoxysilane (Silquest A-Link 15), N-phenyl-gamma-aminopropyltrimethoxysilane (Silquest Y-9669), 4-amino-3,3-dimethylbutyltrimethoxysilane (Silquest A-1637), ((cyclohexylamino)methyl)(diethoxy)methylsilane (GENIOSIL XL 924), N-cyclohexylaminomethyltriethoxysilane (GENIOSIL XL 926), N-(phenylaminomethyl)trimethoxysilane (GENIOSIL XL 973) or mixtures thereof.

In a preferred embodiment, the optionally present protective layer has the composition disclosed in the respective main claims of WO 2006/021386 A1, WO 2012/130897 A1 or WO 2014/053454 A1.

In addition, the red effect pigments of the invention may have been provided with a surface modification which, for example, facilitates the incorporation of the effect pigments into different media. In the case of use of the red effect pigments of the invention in powder coatings, for example, the effect pigments preferably have one of the surface modifications disclosed in the main claims of EP 2 698 403 A1 or of EP 2 576 702 A1. Alternatively, the red effect pigments of the invention may have an outermost coating according to WO 2006/136435 A2, claim 32, which is preferably applied by the spray drying method according to WO 2006/136435 A2, claim 1.

In the case of use of the red effect pigments of the invention in cosmetic formulations, the incorporation thereof into O/W, W/O or W/Si emulsion systems can be facilitated by hydrophobic surface coverage, for example with triethoxycaprylylsilane, and more prolonged emulsion stability can be achieved.

The red effect pigments of the invention can also be used in mixtures with transparent and/or hiding (in)organic white, chromatic or black pigments and/or metal effect pigments and/or pearlescent pigments and/or fillers in the application desired in each case. The amount in which the red effect pigments of the invention are used depends on the particular application and on the optical effect to be achieved.

The red effect pigments of the invention can be used in cosmetic formulations, plastics, films, textiles, ceramic materials, glasses, paints, printing inks, writing inks, lacquers and powder coatings. In addition, the red effect pigments of the invention can also be used for functional applications, for example laser marking, greenhouse films or agricultural films.

In cosmetic formulations, for example body powder, face powder, pressed or loose powder, powder cream, eye makeup such as eyeshadow, mascara, eyeliner, liquid eyeliner, eyebrow pencil, lip balm, lipstick, lip gloss, lip liner, hair styling compositions such as hair spray, hair mousse, hair gel, hair wax, hair mascara, permanent or semipermanent hair dyes, temporary hair dyes, skincare compositions such as lotions, gels, emulsions, nail varnish compositions, it is possible to combine the red effect pigments of the invention with raw materials, auxiliaries and active ingredients suitable for the particular application. The total concentration of red effect pigments of the invention in the cosmetic formulation may be between 0.001% by weight for rinse-off products and 40.0% by weight for leave-on products, based in each case on the total weight of the formulation.

In a further embodiment, the red effect pigments of the invention may be in compact particulate form. Compact particulate form is understood to mean pallets in the form of preferably cylinders and/or beads. The cylinders here preferably have a diameter from a range from 0.2 cm to 4.2 cm, more preferably from a range from 0.5 cm to 2.3 cm and most preferably from a range from 0.7 cm to 1.7 cm, and preferably a length from a range from 0.2 cm to 7.1 cm, more preferably from a range from 0.6 cm to 5.3 cm and most preferably from a range from 0.8 cm to 3.7 cm. The beads preferably have a radius of 1 cm, more preferably from a range from 0.2 cm to 0.7 cm and most preferably from a range from 0.3 cm to 0.5 cm.

In one embodiment, the present invention relates to a red effect pigment comprising a nonmetallic substrate in platelet form, preferably a synthetic mica platelet or a glass platelet, and a coating applied to the substrate, wherein the coating comprises at least one metal oxide, metal hydroxide and/or metal oxide hydrate, the metal ions of the metal oxide, metal hydroxide and/or metal oxide hydrate comprise at least two different metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr, the proportion of iron ions, determined by means of XRF and calculated as the elemental iron, totals at least 18% by weight, based on the total weight of the red effect pigment, and where the hue angle h*15 in the CIE LCh color space is within a range from 330° to 360° and 0° to 50°, and where the aspect ratio of the red effect pigment, defined as D₅₀/total thickness, is within a range from 1 to 5000, preferably within a range from 5 to 1000, more preferably within a range from 10 to 790.

In a further embodiment, the present invention relates to a red effect pigment comprising a nonmetallic substrate in platelet form, preferably a synthetic mica platelet or a glass platelet, and a coating applied to the substrate, wherein the coating comprises at least one metal oxide, metal hydroxide and/or metal oxide hydrate, the metal ions of the metal oxide, metal hydroxide and/or metal oxide hydrate comprise at least two different metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr, the proportion of iron ions, determined by means of XRF and calculated as the elemental iron, total is at least 18% by weight, based on the total weight of the red effect pigment, and where the hue angle h*₁₅ in the CIE LCh color space is within a range from 340° to 360° and 0° to 50°, and where the total thickness of the red effect pigment, defined as the sum total of mean thickness of the substrate and mean thickness of the overall coating, is within a range from 100 nm to 5000 nm, preferably within a range from 200 nm to 2500 nm, more preferably within a range from 250 nm to 1800 nm.

In a further embodiment, the present invention relates to a red effect pigment comprising a nonmetallic substrate in platelet form, preferably a synthetic mica platelet or a glass platelet, and a coating applied thereto, wherein the coating comprises

-   a) optionally a layer 1 comprising or consisting of tin oxide, tin     hydroxide and/or tin oxide hydrate, -   b) a layer 2 comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate, where the metal ion comprises or is at     least one metal ion selected from the group of metals consisting of     Fe, Sn, Ti and Zr, -   c) a layer 3 comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate, where the metal ion comprises or is at     least one metal ion selected from the group of metals consisting of     Fe, Sn, Ti and Zr,     where at least one of layers 2 and 3 comprises at least two     different metal ions from the groups listed above and at least one     of layers 2 and 3 comprises iron ions, where the proportion of iron     ions, determined in each case via XRF and calculated in each case as     the elemental metal, is within a range from 22% by weight to 79% by     weight, based on the total weight of the effect pigment, layers 2     and 3 are interrupted by a spacer layer of mean height h_(a) from a     range from 5 nm to 76 nm, the standard deviation of the relative     height h_(Rma) is within a range from 0.2% to 11%, and the network     density is within a range from 0.5% to 79%.

What is meant by “interrupted” in accordance with the invention is that layers 2 and 3 are spaced apart or kept at a distance from one another by a spacer layer.

What is meant by the general expression “metal oxide, metal hydroxide and/or metal oxide hydrate” in accordance with the invention is “metal oxide and/or metal hydroxide and/or metal oxide hydrate”. This is also true when the metal or metal ion is specified, for example as titanium (ion), iron (ion), tin (ion), zirconium (ion) etc.

In a preferred embodiment, the optional layer 1 directly adjoins the nonmetallic substrate in platelet form, layer 2 directly follows layer 1 and layer 3 follows layer 2, with layers 2 and 3 interrupted by a spacer layer.

In a further embodiment, layer 2 directly adjoins the nonmetallic substrate in platelet form which has been coated with at least one metal oxide, metal hydroxide and/or metal oxide hydrate, and layer 3 follows layer 2, with layers 2 and 3 interrupted by a spacer layer. The outer metal oxide, metal hydroxide and/or metal oxide hydrate layer of the nonmetallic substrate in platelet form here comprises at least one metal ion selected from the group of metals consisting of Fe, Ti and Zr.

In a further embodiment, the present invention relates to a red effect pigment comprising a nonmetallic substrate in platelet form, preferably a synthetic mica platelet or a glass platelet, and a coating applied thereto, wherein the coating comprises

-   a) optionally a layer 1 comprising or consisting of tin oxide, tin     hydroxide and/or tin oxide hydrate, -   b) a layer 2 comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate, where the metal ion comprises or is at     least one noncoloring metal ion selected from the group of metals     consisting of Fe and Sn, -   c) a layer 3 comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate, where the metal ion comprises or is at     least one noncoloring metal ion selected from the group of metals     consisting of Fe and Sn,     and at least one of layers 2 and 3 comprises at least two different     metal ions from the groups listed above and at least one of layers 2     and 3 comprises iron ions, layers 2 and 3 are interrupted by a     spacer layer, and where the effect pigments have a span ΔD from a     range from 0.8 to 2.5.

In a preferred embodiment, the present invention relates to a red effect pigment comprising a nonmetallic substrate in platelet form, preferably a synthetic mica platelet or a glass platelet, and a coating applied thereto, wherein the coating comprises

-   a) optionally a layer 1 comprising or consisting of tin oxide, tin     hydroxide and/or tin oxide hydrate, -   a) a layer 2 comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate composed of or comprising at least one     metal ion selected from the group of metals consisting of Ti, Fe, Sn     and Zr, -   b) a layer 3 comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate composed of or comprising at least one     metal ion selected from the group of metals consisting of Ti, Fe, Sn     and Zr,     and at least one of layers 2 and 3 comprises at least two different     metal ions from the groups listed above and at least one of layers 2     and 3 comprises iron ions, where the proportion of iron ions,     determined in each case via XRF and calculated in each case as the     elemental metal, is within a range from 21% by weight to 78% by     weight in total, preferably within a range from 25% by weight to 72%     by weight, based in each case on the total weight of the effect     pigment, layers 2 and 3 are interrupted by a spacer layer and the     effect pigment has a chemical resistance with a dE of <5, preferably     <3.

In a particularly preferred embodiment, the present invention relates to a red effect pigment comprising a nonmetallic substrate in platelet form, preferably a synthetic mica platelet or a glass platelet, and a coating applied thereto, wherein the coating comprises

-   a) optionally a layer 1 comprising or consisting of tin oxide, tin     hydroxide and/or tin oxide hydrate, -   b) a layer 2 comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate, where the metal ions comprise or are at     least two metal ions selected from the group of metals consisting of     Fe and Sn, -   c) a layer 3 comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate, where the metal ions comprise or are at     least two metal ions selected from the group of metals consisting of     Fe and Sn,     and layers 2 and 3 are interrupted by a spacer layer, where the     coating comprises further layers of high and/or low refractive index     and the effect pigment comprises at least one further spacer layer     which runs essentially parallel to the surface of the nonmetallic     substrate in platelet form and is of mean height h_(a) from a range     from 4 nm to 100 nm, preferably from a range from 9 nm to 74 nm.

In a further embodiment, the present invention relates to a red effect pigment comprising a nonmetallic substrate in platelet form, preferably a synthetic mica platelet or a glass platelet, and a coating applied thereto, wherein the coating comprises

-   a) optionally a layer 1 comprising or consisting of tin oxide, tin     hydroxide and/or tin oxide hydrate, -   b) a layer 2 comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate, where the metal ion comprises or is at     least one metal ion selected from the group of metals consisting of     Zr, Sn and Fe, -   c) a layer 3 comprising at least one metal oxide, metal hydroxide     and/or metal oxide hydrate, where the metal ion comprises or is at     least one metal ion selected from the group of metals consisting of     Zr, Sn and Fe,     where at least one of the layers 2 and 3 comprises at least two     different metal ions from the groups listed above and at least one     of layers 2 and 3 comprises iron ions, the quotient of the mean     layer thickness of layer 2 and the mean layer thickness of layer 3     is preferably within a range from 0.5 to 3.0, and the standard     deviation of the relative height h_(Rma) is within a range from 0.2%     to 11%.

In a further embodiment, the present invention relates to a red effect pigment comprising a nonmetallic substrate in platelet form, preferably a synthetic mica platelet or a glass platelet, and a coating applied thereto, where the coating has through at least one spacer layer essentially parallel to the surface of the nonmetallic substrate in platelet form and the effect pigment is obtainable by i) optionally applying an uncalcined tin oxide, tin hydroxide and/or tin oxide hydrate layer to the nonmetallic substrate in platelet form, ii) applying three uncalcined metal oxides, metal hydroxides and/or metal oxide hydrates, where the second of these uncalcined metal oxides, metal hydroxides and/or metal oxide hydrates is physically different from the others and is of such a nature that it can diffuse into at least one of the other uncalcined metal oxides, metal hydroxides and/or metal oxide hydrates, where the first and third of the three uncalcined metal oxides, metal hydroxides and/or metal oxide hydrates each comprise or are at least one metal ion selected from the group of metals consisting of Fe, Ti and Zr, the first and/or third of the three uncalcined metal oxides, metal hydroxides and/or metal oxide hydrates comprise or are iron ions and the second of the three uncalcined metal oxides, metal hydroxides and/or metal oxide hydrates comprises or is at least one metal ion selected from the group of metals consisting of Sn, Ti and Zr, and iii) calcining the product obtained in step ii), optionally under reducing conditions, at a temperature from a range from 400° C. to 980° C.

In a very particularly preferred embodiment, the present invention relates to a red effect pigment comprising a nonmetallic substrate in platelet form, preferably a synthetic mica platelet or a glass platelet, and a coating applied thereto, where the coating has at least one spacer layer which is essentially parallel to the surface of the nonmetallic substrate in platelet form and is of mean height h_(a) from a range from 14 nm to 51 nm, and the effect pigment is obtainable by i) optionally applying an uncalcined tin oxide, tin hydroxide and/or tin oxide hydrate layer using a water-soluble tin(IV) salt to the nonmetallic substrate in platelet form, ii) sequentially applying a first layer A using a water-soluble iron(III) salt, a second layer B using a water-soluble tin(IV) salt and/or titanium(IV) salt, a third layer C using a water-soluble iron(III) salt, and iii) calcining the product obtained in step ii) at a temperature from a range from 400° C. to 910° C.

In a preferred embodiment, the coating of the red effect pigments of the invention, in each case prior to drying and/or calcination, comprises at least one layer of high refractive index composed of comprising titanium oxide, titanium hydroxide and/or titanium oxide hydrate and at least two nonadjacent layers of high refractive index composed of or comprising iron oxide, iron hydroxide and/or iron oxide hydrate, where the weight ratio in the effect pigment of titanium to iron is <1, preferably within a range from 0.01 to 0.8 and more preferably within a range from 0.1 to 0.5 and most preferably within a range of 0.05 and 0.19.

In a further-preferred embodiment, the coating of the red effect pigments of the invention, in each case prior to drying and/or calcination, comprises at least one layer of high refractive index composed of or comprising tin oxide, tin hydroxide and/or tin oxide hydrate and at least two layers of high refractive index composed of or comprising iron oxide, iron hydroxide and/or iron oxide hydrate, where the weight ratio in the effect pigment of tin to iron is <1, preferably within a range from 0.01 to 0.9 and more preferably within a range from 0.1 to 0.8. In this embodiment, it is especially preferable that first at least one high-refractive index layer of iron oxide, iron hydroxide and/or iron oxide hydrate and then at least one high-refractive index layer of tin oxide, tin hydroxide and/or tin oxide hydrate and a further high-refractive index layer of iron oxide, iron hydroxide and/or iron oxide hydrate are applied directly to the substrate in platelet form or directly to the respective uppermost layer close to the substrate. In addition, it is also possible, prior to application of the at least one high-refractive index layer of iron oxide, iron hydroxide, iron oxide hydrate, to deposit a layer or preliminary coverage with metal oxides, metal hydroxides, metal oxide hydrates, where the metal ion comprises or is a metal ion selected from the group of metals consisting of Sn and Si, directly to the nonmetallic substrate in platelet form or directly to the respective uppermost layer close to the substrate, where the layer thickness may be a few nanometers, preferably less than 10 nm, more preferably less than 5 nm and most preferably less than 3 nm, and said layer need not fully surround the substrate. The tin oxide, tin hydroxide and/or tin oxide hydrate may be present at least partly in a mixed layer with the iron oxide, iron hydroxide and/or iron oxide hydrate.

In a further embodiment, the present invention relates to a red effect pigment comprising a nonmetallic substrate in platelet form, preferably a synthetic mica platelet or a glass platelet, and a coating applied to the substrate, where the coating has at least one spacer layer essentially parallel to the surface of the nonmetallic substrate in platelet form and the effect pigment has been calcined under reducing conditions or has a semitransparent metal layer in the overall coating, preferably as the outermost layer directly beneath an optionally present protective layer.

In one embodiment, the coating of the red effect pigments of the invention, rather than the at least one metal oxide, metal hydroxide and/or metal oxide hydrate, comprises the corresponding metal suboxides, metal fluorides, metal nitrides, metal oxynitrides, metal oxyhalides and/or metal sulfides.

In one embodiment, the coating of the red effect pigments of the invention comprises, in addition to the at least one metal oxide, metal hydroxide and/or metal oxide hydrate, at least one metal suboxide, metal fluoride, metal nitride, metal oxynitride, metal oxyhalide and/or metal sulfide.

There follows an elucidation of the invention by a few examples, but the examples do not restrict the invention. All % figures in the examples and comparative examples should be understood as % by weight.

I PRODUCTION OF THE RED EFFECT PIGMENTS OF THE INVENTION Example 1

200 g of synthetic mica platelets (fluorphlogopite platelets) having a particle size distribution according to MALVERN Mastersizer MS 2000: D₁₀=11 μm, D₅₀=21 μm, D₉₀=36 μm were suspended in 1300 mL of demineralized water and heated to 85° C. with turbulent stirring. The pH of the suspension was adjusted to pH 2.6. By addition of 570 g of an aqueous iron chloride solution having a density of 1.42 g/cm³, a layer of iron oxide was deposited on the surface of the synthetic mica platelets. After the mixture had been stirred for a further 60 min, the pH of the suspension was lowered to pH 2.2 and then a solution of 500 mL of SnCl₄ having a concentration of 30 g of Sn/L was dosed into the suspension. Then the mixture was stirred for another 120 minutes and then 750 g of an aqueous iron chloride solution having a density of 1.42 g/cm³ were added. 60 minutes after the addition had ended, the suspension was filtered off and the filtercake was washed. The filtercake was dried if necessary and calcined at 800° C. for 45 minutes. Extremely chromatic, high-gloss red interfering effect pigments with red absorption color and very good hiding power were obtained.

Example 2

200 g of synthetic mica platelets (fluorphlogopite platelets) having a particle size distribution according to MALVERN Mastersizer MS 2000: D₁₀=10 μm, D₅₀=22 μm, D₉₀=40 μm were suspended in 1300 mL of demineralized water and heated to 85° C. with turbulent stirring. The pH of the suspension was adjusted to pH 2.6. By addition of 570 g of a an aqueous iron chloride solution having a density of 1.42 g/cm³, a layer of iron oxide was deposited on the surface of the synthetic mica platelets. The pH of the suspension was lowered thereafter to pH 1.9 and then a solution of 250 mL of TiCl₄ (200 g of TiO₂/L of demineralized water) was dosed into the suspension.

Then the mixture was stirred for another 120 minutes and then 600 g of an aqueous iron chloride solution having a density of 1.42 g/cm³ were added. 60 minutes after the addition had ended, the suspension was filtered off and the filtercake was washed. The filtercake was dried if necessary and calcined at 400° C. for 60 minutes. Extremely chromatic, high-gloss red interfering effect pigments with red absorption color and very good hiding power were obtained.

Example 3

200 g of synthetic mica platelets (fluorphlogopite platelets) having a particle size distribution according to MALVERN Mastersizer MS 2000: D₁₀=7 μm, D₅₀=20 μm, D₉₀=35 μm were suspended in 1300 mL of demineralized water and heated to 85° C. with turbulent stirring. The pH of the suspension was adjusted to pH 2.6, and 530 g of an aqueous iron chloride solution having a density of 1.42 g/cm³ were added. After the mixture had been stirred for a further 60 min, the pH of the suspension was lowered to pH 2.2 and then a solution of 17.5 mL of SnCl₄ having a concentration of 315 g of Sn/L was dosed into the suspension.

Then the mixture was stirred for another 120 minutes and then 1000 g of an aqueous iron chloride solution having a density of 1.38 g/cm³ were added. 60 minutes after the addition had ended, the suspension was filtered off and the filtercake was washed. The filtercake was dried if necessary and calcined at 780° C. for 45 minutes. Extremely chromatic, high-gloss red interfering effect pigments with red absorption color and very good hiding power were obtained.

Example 4

200 g of synthetic mica platelets (fluorphlogopite platelets) having a particle size distribution according to MALVERN Mastersizer MS 2000: D₁₀=9 μm, D₅₀=19 μm, D₉₀=37 μm were suspended in 1300 mL of demineralized water and heated to 85° C. with turbulent stirring. The pH of the suspension was adjusted to pH 2.2 and then a solution of 50 mL of SnCl₄ having a concentration of 30 g of Sn/L was metered in at constant pH. Subsequently, the mixture was stirred for a further 60 minutes and the pH was adjusted to 1.9 and 800 mL of TiCl₄ solution (200 g of TiO₂/L of demineralized water) were added. After stirring for another 60 min, the pH of the suspension was lowered to pH 2.2 and then a solution of 500 mL of SnCl₄ having a concentration of 30 g of Sn/L was dosed into the suspension. Then the mixture was stirred for another 120 minutes and then 1200 g of an aqueous iron chloride solution having a density of 1.38 g/cm³ were added. 60 minutes after the addition had ended, the suspension was filtered off and the filtercake was washed. The filtercake was dried if necessary and calcined at 830° C. for 45 minutes. Extremely chromatic, high-gloss red interfering effect pigments with red absorption color and very good hiding power were obtained.

Example 5

150 g of synthetic mica platelets (fluorphlogopite platelets) having a particle size distribution according to MALVERN Mastersizer MS 2000: D₁₀=8 μm, D₅₀=20 μm, D₉₀=36 μm were suspended in 1200 mL of demineralized water and heated to 85° C. with turbulent stirring. The pH of the suspension was adjusted to pH 2.6, and 350 g of an aqueous iron chloride solution having a density of 1.42 g/cm³ were added. After the mixture had been stirred for a further 60 minutes, the pH of the suspension was adjusted to pH 3.5 and then a solution of 110 mL of zirconium chloride w(ZrCl₄)=20.0% by weight was dosed into the suspension.

Then the mixture was stirred for another 120 minutes, the pH was adjusted to 2.6 and then 700 g of an aqueous iron chloride solution having a density of 1.38 g/cm³ were added. 60 minutes after the addition had ended, the suspension was filtered off and the filtercake was washed. The filtercake was dried if necessary and calcined at 800° C. for 60 minutes. Extremely chromatic, high-gloss red interfering effect pigments with red absorption color and very good hiding power were obtained.

Example 6

200 g of synthetic borosilicate glass platelets having a particle size distribution according to MALVERN Mastersizer MS 2000: D₁₀=34 μm, D₅₀=57 μm, D₉₀=95 μm were suspended in 1300 mL of demineralized water and heated to 85° C. with turbulent stirring. Then the following were added successively: 40 mL of SnCl₄ (concentration 53 g/l) at pH 2.2, 122 mL of FeCl₃ (density 1.42 g/cm³) at pH 2.6, 19 mL of TiCl₄ (conc. 200 g TiO₂/L) at pH 1.9 and finally 292 mL of FeCl₃ (density 1.42 g/cm³) at pH 2.6. The pH was kept constant in each case by means of synchronous addition of aqueous NaOH (35%).

60 minutes after the addition had ended, the suspension was filtered off and the filtercake was washed. The filtercake was dried if necessary and calcined at 650° C. for 60 minutes. Extremely chromatic, high-gloss, red-sparkling effect pigments with red absorption color and red reflection color were obtained.

Example 7

The end product from example 4 was calcined under reducing conditions at 450° C. for 15 minutes. Highly chromatic, glossy red interfering effect pigments with a dark absorption color were obtained.

Example 8

100 g of the effect pigment obtained from example 1 were suspended in 850 mL of demineralized water and heated to 85° C. with turbulent stirring. The pH was lowered to pH 4.2 with dilute hydrochloric acid. Then a solution of 0.93 g of Ce(NO₃)₃×6 H₂O dissolved in 40 mL of demineralized water was metered in. At the same time, the pH was kept constant by dropwise addition of a 10% NaOH solution. Once the solution had been added completely, the mixture was stirred for a further hour and the pH was adjusted thereafter to pH 10 with dilute sodium hydroxide solution. Thereafter, 5.7 g of Dynasylan 1146 diluted with 24.3 g of demineralized water were added to the suspension, the suspension was stirred for another 180 minutes and filtered, and the filtercake was washed with demineralized water. The filtercake was dried at 95° C. under reduced pressure.

Comparative Example 1

Red effect pigment based on natural mica platelets, coated with iron oxide, Iriodin 504 Red, from Merck.

Comparative Example 2

Red effect pigment based on SiO₂ platelets, coated with iron oxide, Iriodin 4504 Lava Red, from Merck.

Comparative Example 3

200 g of synthetic mica platelets (fluorphlogopite platelets) having a particle size distribution according to MALVERN Mastersizer MS 2000: D₁₀=10 μm, D₅₀=22 μm, D₉₀=40 μm were suspended in 1300 mL of demineralized water and heated to 85° C. with stirring. The pH of the suspension was adjusted to pH 2.6 and then a solution of 60 mL of FeCl₃ (280 g of Fe₂O₃/L of demineralized water) was metered into the suspension. Subsequently, the suspension was stirred for a further 60 min, before the pH was raised to 7.5 with alkali and the mixture was stirred for a further 20 min. A waterglass solution (185 g of waterglass solution, 24% SiO₂, mixed with 207 g of demineralized water) was then introduced gradually into the suspension. Thereafter, the mixture was stirred for a further 60 min and the pH was adjusted again to 2.6. Then a solution of 260 mL of FeCl₃ (280 g of Fe₂O₃/L of demineralized water) was metered into the suspension. Lastly, the mixture was stirred for a further 60 minutes, then the suspension was filtered and the filtercake was washed. The filtercake was calcined at 780° C. for 45 minutes. A red-interfering, red-absorbing multilayer pearlescent pigment with comparatively low chroma was obtained.

Comparative Example 4

Red effect pigment based on glass platelets, coated with iron oxide, MIRAGE Sparkling Red, from Eckart.

Comparative Example 5

In accordance with example 1 of U.S. Pat. No. 8,585,818 B1, a suspension of synthetic mica of the 20-80 μm fraction with a D₅₀ of 35 μm in 1785 mL of demineralized water was heated to 83° C. and the pH was adjusted to 1.4 with HCl. 50 g of a 20% SnCl₄ solution were metered in at a metering rate of 3.2 g/min and the pH was kept constant with NaOH. Subsequently, the mixture was stirred for a further 60 minutes and then 36 g of a 40% TiCl₄ solution were added at 3 g/min. Here too, the pH was kept constant with NaOH. Subsequently, the pH was adjusted to 3.0, before an iron chloride solution w(FeCl₃)=39% was added at a rate of 1.2 g/min at a constant pH. After 320 mL of FeCl₃ had been added, the suspension was filtered, washed and calcined at 850° C. A bronze pigment with moderate effect properties was obtained. No spacer layer is apparent in the SEM transverse section.

II CHARACTERIZATION OF THE RED EFFECT PIGMENTS AND PIGMENTS FROM THE COMPARATIVE EXAMPLES IIa Particle Size Measurement

The size distribution curve of the red effect pigments of the invention and of the pigments from the comparative examples was determined using the Malvern Mastersizer 2000 instrument according to the manufacturer's instructions. For this purpose, about 0.1 g of the respective pigment was introduced into the sample preparation cell of the measuring instrument by means of a Pasteur pipette as an aqueous solution, without addition of dispersing aids, with constant stirring, and analyzed repeatedly. The individual measurement results were used to form the medians. The scattered light signals were evaluated by the Fraunhofer method.

The median particle size D₅₀ in the context of this invention is understood to mean the D₅₀ of the cumulative frequency distribution of the volume-averaged size distribution function, as obtained by laser diffraction methods. The D₅₀ indicates that 50% of the pigments have a diameter equal to or less than the value reported, for example 20 μm. Correspondingly, the D₁₀ and D₉₀ respectively state that 10% and 90% of the pigments have a diameter equal to or less than the respective measured value. The span ΔD, defined as

${{\Delta \; D} = \frac{D_{90} - D_{10}}{D_{50}}},$

indicates the breadth of the particle size distribution.

TABLE 3 Particle sizes Example/comparative example D₁₀ [μm] D₅₀ [μm] D₉₀ [μm] Span Example 1 10.0 21.9 40.2 1.382 Example 2 8.8 20.1 37.6 1.429 Example 3 8.3 20.7 40.8 1.567 Example 4 9.2 20.7 39.7 1.475 Example 5 10.1 21.8 40.3 1.384 Example 6 27.2 54.0 97.4 1.299 Example 7 8.4 20.4 40.7 1.583 Comparative example 1 10.8 21.9 41.5 1.402 Comparative example 2 9.7 19.3 35.5 1.337 Comparative example 3 17.2 28.9 47.0 1.031 Comparative example 4 29.4 56.4 98.0 1.219 Comparative example 5 17.4 36.2 63.9 1.285

IIb Angle-Dependent Color Measurements

To measure the color and brightness values, the effect pigments of the invention and the pigments from the comparative examples were stirred into a conventional nitrocellulose lacquer (Erco 2615e bronze mixing lacquer colorless; from Maeder Plastiklack AG) at a pigmentation level of 6% by weight, based on the total weight of the wet lacquer. This was done by initially charging the respective pigments and then dispersing them into the lacquer with a brush. The finished lacquer was applied to black/white hiding charts (Byko-Chart 2853, from Byk-Gardner) in a wet film thickness of 40 μm, 76 μm (example 6) or 100 μm with a spiral applicator on an applicator drawdown apparatus (RK Print Coat Instr. Ltd. Citenco K 101 drawdown apparatus), and subsequently dried at room temperature. The choice of spiral applicator is made according to table 2 depending on the D₅₀ of the pigments or substrates to be applied in each case.

The BYK-mac multi-angle colorimeter (from Byk-Gardner) was used to determine the color values on the black background of the hiding chart at a constant angle of incidence of 45° (according to the manufacturer's instructions) at various observation angles relative to the specular angle. Characterization of the color intensity was accomplished using the chroma value C*₁₅, which was measured at a measurement angle separated by 15° from the specular angle on the black background of the black/white hiding chart.

Strongly reflecting samples (mirrors in the ideal case) reflect virtually all the incident light at what is called the specular angle. The closer to the specular angle the measurement is made on the lacquer application, the more intense the appearance of the interference color.

TABLE 4 Color and brightness values of the red effect pigments of the invention Example/ comparative NC lacquer 6% 40 μm BykMac example L* 110° s¹⁾ a*15° s b*15° s C* 15° s h* 15° s Example 1 70.7 52.8 32.0 61.7 31.2 Example 2 64.2 40.2 27.6 48.8 34.5 Example 3 75.7 50.1 23.3 55.3 24.9 Example 4 59.6 31.9 22.7 39.1 35.4 Example 5 63.7 46.2 29.8 54.9 32.8 Example 6 67.4 40.1 36.7 54.3 42.5 Example 7 60.2 26.4 15.5 30.6 30.4 Comparative 74.5 38.6 11.4 40.2 16.5 example 1 Comparative 73.7 48.7 29.1 56.8 30.8 example 2 Comparative 59.6 20.1 9.6 22.3 25.4 example 3 Comparative 37.4 13.9 8.7 16.4 32.1 example 4 Comparative 83.0 5.8 24.4 25.1 76.7 example 5 ¹⁾Measured on the black background of the black/white hiding chart.

IIc Comparison of Hiding

To determine the hiding quotient D_(q), defined as

${D_{q} = \frac{L_{black}^{*110}}{L_{white}^{*110}}},$

lacquer applications analogous to IIb but with a pigmentation level of 10% by weight were and applied with a spiral applicator in a wet film thickness of 100 μm to black/white hiding charts (Byko-Chart 2853, from Byk-Gardner) and subsequently dried at room temperature. Subsequently, the brightness values L*110° of the lacquer applications were recorded with the BYK-mac multi-angle colorimeter (from Byk-Gardner) at a measurement angle of 110° on the black and white backgrounds of the black/white hiding chart. The 110° measurement geometry, at a constant angle of incidence of 45°, relates to the difference from the specular angle. The viewing angle is measured away from the specular reflection in the plane of illumination.

The effect pigments of the invention have good hiding power. The hiding quotient D_(q) thereof is preferably ≧0.41. The hiding quotient D_(q) of the inventive red effect pigments in platelet form from examples 1 to 6, as can be inferred from table 6, is in each case well above 0.41.

IId Gloss Measurements

Gloss is a measure of directed reflection. To determine the gloss, the paint applications from IIb on the white background of the black/white hiding chart were analyzed at a measurement angle of 60° based on the vertical with the aid of a Micro-Tri-Gloss gloss meter from Byk-Gardner. The gloss values of the red effect pigments of the invention and of the pigments from the comparative examples are listed in table 5.

Some of the inventive red effect pigments in platelet form from examples 1 to 6 show distinctly higher gloss values than the pigments having a single-layer coating from comparative examples 1 and 2.

The gloss measurements from table 5 confirm the very high reflectivity of the pigments of the invention compared to the prior art.

TABLE 5 Gloss values Example/comparative example 60° gloss (w) Example 1 46.6 Example 2 53.9 Example 3 37.6 Example 4 42.4 Example 5 42.7 Example 6 51.4 Example 7 50.4 Comparative example 1 41.8 Comparative example 2 32.3

IIe Effect Measurements

In order to objectively describe the optical effect of the red effect pigments of the invention, effect measurements were conducted with the BYK-mac spectrophotometer (from Byk-Gardner) using the lacquer applications from IIb (cf. Byk-Gardner catalog “Qualitātskontrolle für Lacke and Kunststoffe” [Quality Control for Lacquers and Plastics], 2011/2012, p. 97/98). The corresponding measurement values for the sparkle intensity S_i, the sparkle area S_a and the graininess G are collated in table 6.

TABLE 6 Effect measurements, hiding quotient and gloss values Example/comparative S_i 15° example (s)¹⁾ S_a 15° (s)¹⁾ G (s)¹⁾ D_(q) 110°²⁾ Example 1 7.33 30.04 4.77 0.939 Example 2 6.35 27.85 4.68 0.923 Example 3 5.69 25.00 4.23 0.955 Example 4 8.61 31.31 4.41 0.922 Example 5 6.23 29.01 4.04 0.967 Example 6 21.70 37.58 8.12 0.590 Comparative example 1 4.70 19.38 4.15 0.800 Comparative example 2 4.28 18.57 3.45 / Comparative example 3 7.12 27.03 4.92 / Comparative example 4 21.81 27.46 5.05 / Comparative example 5 / / / 0.673 ¹⁾Measured on the black background of the black/white hiding chart. ²⁾Measured on a 10% NC lacquer drawdown, wet film thickness 100 μm

The effect values S_i, S_a and G of the inventive red effect pigments in platelet form from examples 1 to 6 are usually higher than the values for the comparative examples. The achievable optical effects of the inventive red effect pigments in platelet form are much more marked than in the case of conventional effect pigments with a single-layer coating from comparative examples 1 and 2.

IIf Waring Blender

In industry, many lacquers are processed in circulation systems. In this case, the lacquer components are subjected to high shear forces. The Waring blender test simulates these conditions and serves for assessment of the ring line stability/shear stability. Specifically pigments wherein the coating has not been adequately anchored on the support material exhibit significant deviations in the chroma values in this test compared to the untreated applications. The Waring blender test can thus be regarded as a measure of the mutual adhesion of the pigment coating with respect to shear forces.

For this purpose, the red effect pigments of the invention or the pigments from the comparative examples were weighed out according to the recipe below and converted stepwise to a paste with a conventional acrylic lacquer in an 880 mL beaker. Thereafter, the viscosity was adjusted with butyl acetate/xylene 1:1 to 17″ in the DIN 4 mm cup. A total of 600 g of lacquer were produced, of which 400 g were introduced into a jacketed water-cooled 1 kg vessel and stirred with a specific attachment under the Dispermat (from Waring Blenders). The stirring time was 8 minutes at 13 500 rpm, then 200 g of lacquer were removed and the rest was stirred for a further 12 minutes.

-   Recipe: 6% pigment     -   8% butyl acetate 85     -   86% acrylic lacquer, colorless     -   30% dilution butyl acetate 85/xylene 1:1

200 g each of the untreated and treated lacquers were applied to a test sheet with a spraying machine and the Sata LP-90 spray gun according to the following settings:

-   Setting: Needle: 1.3.4     -   Pressure: 4 bar -   Runs: The number of spray runs was chosen such that there was a dry     lacquer layer thickness of 15-20 μm.

Conventionally, effect pigments are regarded as being shear-stable when the gloss differential and the color differential, measured close to the specular angle, is relatively low in the application after the Waring blender test. The ΔC*₁₅ value relative to the untreated sample should ideally be less than 2. Table 7 shows the change in color ΔC*₁₅ and the change in gloss Δ60° gloss of the sample that has been subjected to the Waring blender test relative to the untreated sample for inventive examples 1 and 3.

TABLE 7 Gloss differential and color differential in the Waring blender test ΔC* (15°) Δgloss (60°) Example 1 1.15 −1.3 Example 3 2.31 −2.6

The red effect pigments of the invention from examples 1 and 3 fulfill the criteria of the test. The color difference is negligibly small. Even under the microscope, it is barely possible to detect any changes such as flaking of the coating or other surface defects that have arisen.

The red effect pigments of the invention are found to be extremely shear-stable in spite of their spacer layer.

IIg Determination of Chemical Stability

The chemical stability of the red effect pigments of the invention and of the pigments from the comparative examples was determined with reference to applications of lacquer to plastic panels. 6 g of the respective pigment were stirred into a mixture of 90 g of a conventional colorless acrylic lacquer and 10 g of butyl acetate 85. Thereafter, the viscosity was adjusted with a mixture of butyl acetate 85 and xylene in a ratio of 1:1 to 17″ in the DIN 4 mm cup.

100 g of this lacquer in each case were applied to the panels in hiding application analogously to IIf with a spraying machine. After the coating, the panels were baked at 80° C. for 30 minutes. 24 hours later, the panels were immersed to half their height into 10% sodium hydroxide solution. After a contact time of 7 days, the panels were rinsed with demineralized water and then, after drying time of 2 hours, assessed visually for damage and/or discoloration. In addition, discoloration was analyzed with the aid of the BYK-mac (from Byk-Gardner). The change in color was characterized using the ΔE value of the exposed sample versus the corresponding unexposed sample at a measurement angle of 15°. The results are shown in table 8 below.

TABLE 8 Color change ΔE Example/comparative example ΔE (15°) Example 1 1.8 Comparative example 3 13.31

Pigments with a ΔE(15°)<3 can be regarded as stable to chemicals. The red effect pigment of the invention from example 1 is below the limit, whereas the pigment from comparative example 3 distinctly exceeds it.

IIh X-Ray Fluorescence Analysis (XRF)

The metal oxide, metal hydroxide and/or metal oxide hydrate contents of the red effect pigments of the invention and of the pigments from the comparative examples were determined by means of x-ray fluorescence analysis (XRF). For this purpose, the respective pigments were incorporated into a lithium tetraborate glass tablet, fixed in solid sample measuring cups and analyzed therefrom. The measuring instrument used was the Advantix ARL system from Thermo Scientific. The measurements are shown in table 9. The figures for the different contents were reported here as TiO₂ for titanium, as Fe₂O₃ for iron, as ZrO₂ for Zr, as SiO₂ for Si, and as SnO₂ for tin.

TABLE 9 Mean height h_(a) of the spacer layer and XRF values Example/ SEM comparative Mean height h_(a) XRF (as oxide) example [nm] Ti [%] Fe [%] Sn [%] Zr [%] Si [%] Example 1 46 / 55.9 3.8 / / Example 2 20 9.1 51.1 / / / Example 3 43 / 59.5 1.4 / / Example 4 56 25.8  34.4 3.4 / Example 5 32 / 54.2 / 4.1 / Example 6 38 2.3 30.5  0.42 / Comparative example 1 no spacer layer / 48.5 / / / Comparative example 2 no spacer layer  0.04 55.7 / / 42.9 Comparative example 3 no spacer layer / / / / / Comparative example 4 no spacer layer 1.1 18   0.5 / / Comparative example 5 no spacer layer 2.1 21.7 2   / /

IIi Condensate Water Test

To determine condensate water stability, the red effect pigments of the invention and the pigments from the comparative examples were incorporated into a waterborne lacquer system and the test applications were produced by spray painting onto aluminum sheets. The basecoat was overcoated with a conventional one-component clearcoat and then baked. These applications were tested according to DIN 50 017 (water condensation—constant atmospheres). Bond strength was tested by means of cross-cutting according to DIN EN ISO 2409 immediately after the end of the test by comparison with the unexposed sample. In this context, Cc 0 means no change and Cc 5 a very significant change.

The swelling characteristics were visually assessed immediately after condensate water exposure in accordance with DIN 53230. In this context, the index 0 means no change and the index 5 a very significant change.

Finally, the DOI (distinctness of image) was determined with the aid of a Wave-scan II from Byk-Gardner.

TABLE 10 Condensate water results 20° gloss 20° gloss Cross- before after Loss of cutting Swelling Sample CW test CW test gloss immediate visual Example 8 91 91 0 1 0 Comparative 89 42 53% 5 4 example 2

The pigment from comparative example 2 had significant swelling characteristics and poor interlayer adhesion. The DOI was no longer measurable because of the high degree of fine structure after condensate water exposure.

The red effect pigment of the invention from example 8, by contrast, was found to be stable and had virtually no changes before and after the test.

IIj Determination of the Mean Thickness of the Nonmetallic Substrates in Platelet Form, the Mean Layer Thickness of Layers 2 and 3, the Mean Layer Thickness of the Overall Coating, the Mean Height h_(a) of the Spacer Layer and the Mean Height h_(H) of the Cavities

For this purpose, the red effect pigments of the invention were incorporated in a concentration of 10% into a two-component clearcoat, Autoclear Plus HS from Sikkens GmbH, with a sleeved brush, applied to a film with the aid of a spiral applicator (wet film thickness 26 μm) and dried. After a drying time of 24 h, transverse sections of these applicator drawdowns were produced. The transverse sections were analyzed by SEM, with analysis of at least 100 individual pigments to be statistically meaningful for determination of the mean thickness of the nonmetallic substrates in platelet form.

To determine the mean layer thickness of layers 2 and 3, the mean thickness of the overall coating, the mean height h_(a) of the spacer layer and the mean height h_(H) of the cavities, the upper and lower substrate surfaces, i.e. the longer side of the nonmetallic substrate in platelet form recognizable in each case in the SEM transverse section, were each used as the baseline. The baseline was drawn here along the surface of the substrate in platelet form in the scanning electron micrograph of the transverse section by connecting the two points of intersection of nonmetallic substrate in platelet form—optional layer 1 or of nonmetallic substrate in platelet form—layer 2 from the left- and right-hand edges of the scanning electron micrograph of the transverse section to one another by means of a straight line. The scanning electron micrographs of transverse sections were analyzed with the aid of the AxioVision 4.6.3 image processing software (from Zeiss).

A sufficient number of parallel lines were drawn at 50 nm intervals at a 90° angle from these two baselines as to place a grid over the complete scanning electron micrograph of the transverse section of the effect pigment (FIG. 4). The magnification of the scanning electron micrograph of the transverse section was preferably at least 50 000-fold, based on Polaroid 545 (4″×5″). Proceeding from the respective upper and lower baselines of the nonmetallic substrate in platelet form in the direction of layer 3 in each case, the distances between the points of intersection of these lines at the respective interfaces of the optional layer 1 with layer 2, of layer 2 with the spacer layer, of spacer layer with layer 3 and of layer 3 with the environment were measured manually. There was an instance here of one of the lines drawn at 50 nm intervals occurring directly above a connection point or a spacer. In this case, only the respective point of intersection of the line at the interface of layer 3 with the environment was recorded. These measurements gave rise to the layer thicknesses of layers 2 and 3, the thickness of the overall coating, the layer thickness of further layers optionally present, and the height h_(a) of the spacer layer by formation of differences.

For the determination of the mean height h_(H) of the cavities, the points of intersection of these parallel lines with the upper and lower cavity boundaries within the spacer layer were used.

The individual values of the layer thicknesses, the height h_(a) and the height h_(H) that have been determined in this way were used to form the respective arithmetic means in order to determine the above-specified values for the mean layer thicknesses, the mean height h_(H) and the mean height h_(a). To be statistically meaningful, the above-described measurements were conducted on at least 100 lines. The term “mean” in all cases means the arithmetic mean.

Transverse sections of the pigments from the comparative examples that do not have a spacer layer but may have statistically distributed pores within the coating were likewise examined by the method described above using scanning electron micrographs of transverse sections. In this case, if one of the parallel lines occurred above one or more pores, the height of the pore(s), the pore midpoint(s) thereof and the distance of the pore midpoint(s) from the substrate surface were determined.

As an alternative to transverse sections, the red effect pigments of the invention can be cut by means of the FIB method (FIB=focused ion beam). For this purpose, a fine beam of highly accelerated ions (for example gallium, xenon, neon or helium) is focused to a point by means of ion optics and guided line by line over the effect pigment surface to be processed. On impact with the effect pigment surface, the ions release most of their energy and destroy the coating at this point, which leads to removal of material line by line. It is also possible using the scanning electron micrographs that have then been recorded, by the method described above, to determine the mean height h_(a), the mean layer thickness of layers 2 and 3 and the mean layer thickness of the overall coating. The mean thickness of the nonmetallic substrate in platelet form can also be determined using scanning electron micrographs of the effect pigments that have been cut by the FIB method.

The advantages of the red effect pigments of the invention are therefore apparent in the sum total of various properties. The red effect pigments of the invention have high transparency, very good mechanical and chemical stability, and high gloss and color intensity. None of the comparative pigments considered overall has all the properties mentioned in a satisfactory manner.

TABLE 11 Characterization of the coating Example/comparative d_(S2) d_(S3) σh_(Rma) example [nm] [nm] d_(S2)/d_(S3) h_(ma) [nm] h_(Rma) [%] n_(S) S_(D) [%] A_(H) [%] Example 1 67 107 0.63 90 0.41 3.10 0.4 2.1 97.9 Example 2 11 82.3 1.44 128.3 0.61 4.50 6.2 30.9 69.1 Example 3 85 96 0.89 107 0.48 1.40 1.0 5.2 94.8 Example 4 11 113 1.00 141 0.500 4.20 0.4 2.1 97.9 Comparative example 1 no spacer layer 24.7 13 65.0 35.0 d_(S2) [nm] = mean layer thickness of layer 2 d_(S3) [nm] = mean layer thickness of layer 3 n_(S) = mean number of bars per μm A_(H) [%] = area proportion of cavity S_(D) = network density [%] h_(ma) = midpoint of the spacer layer (sum total of the layer thickness of the optional layer 1 and of layer 2 and half the height h_(a)) h_(Rma) = relative height of the spacer layer σh_(Rma) [%] = standard deviation of the relative height of the spacer layer

Table 11 shows the mean height h_(a) of the spacer layer of the pigments examined. All the red effect pigments of the invention, by contrast with the pigments from comparative examples 1 to 5, have a spacer layer.

The pigments from comparative examples 1 to 5 do not have any spacer layer. In table 11, for comparative example 1, the value in the σh_(Rma) [%] column means the standard deviation of the pore midpoints from the substrate surface.

Since the pigment from comparative example 1, however, contains only few statistically distributed pores, the network density S_(D) is 65.0%. The standard deviation of the pore midpoints from the substrate surface is 24.7%, which demonstrates that the pores are statistically distributed within the overall coating. The situation is different for the red effect pigments of the invention from examples 1 to 4. Here, the standard deviation of the relative height of the midpoint of the spacer layer h_(Rma) is <5% in each case, which indicates that the respective spacer layer thereof is at a defined position within the coating. The standard deviation of the distances of the pore midpoints from the substrate surface of the pigment from comparative example 1 can thus be compared with the standard deviation of the relative height of the midpoint of the spacer layer of the red effect pigments of the invention.

IIk Scanning Electron Micrographs

The scanning electron micrographs were obtained using transverse sections of the red effect pigments of the invention with the Supra 35 scanning electron microscope (from Zeiss). Energy-dispersive x-ray micro-analysis (EDX analysis) was conducted with the EDAX Sapphire instrument, from EDAX.

III APPLICATION EXAMPLES Application Example 1: Body Lotion

% by Manufacturer/ INCI name Product name wt. supplier Phase A 85.80 Effect pigment from 0.20 example 1 Aqua Water Glycerin Glycerin 85% 2.00 H. Erhard Wagner Xanthan Gum Keltrol CG-T 0.60 CP Kelco Phase B Isopropyl Palmitate Isopropyl palmitate 3.00 H. Erhard Wagner Glyceryl Stearate Aldo MS K FG 2.00 Lonza Cocos Nuifera Oil Ewanol KR 2.00 H. Erhard Wagner Cetearyl Alcohol Tego Alkanol 1618 2.00 Evonik Dimethicone Element 14 PDMS 1.00 Momentive Sodium Polyacrylate Cosmedia SP 0.50 BASF Phase C Phenoxyethanol, Euxyl PE 9010 0.80 Schülke & Meyr ethylhexylglycerin Fragrance Vitamin Bomb 0.10 Bell Europe

The effect pigment from example 1 can be used within a range from 0.1% to 2.5% by weight, based on the total weight of the body lotion formulation. Compensation to 100% by weight of the formulation can be effected with water.

Keltrol CG-T was dispersed in phase A and heated to 75° C. Phase B was heated separately to 75° C. Subsequently, phase B was added gradually to phase A. The emulsion was cooled down to room temperature while stirring and phase C was added individually.

Application Example 2: Eyeshadow Cream

INCI name Product name % by wt. Manufacturer/supplier Phase A Microcrystalline Wax TeCero-Wax 1030 K 4.50 Tromm Wachs Copernicia Cerifera Cera LT 124 carnauba 4.50 Tromm Wachs wax Isohexadecane Isohexadecane 21.00 Ineos Cyclopentasiloxane, Belsil RG 100 8.00 Wacker Dimethicone/Vinyltrimethylsiloxysilicate Silicone Elastomer Crosspolymer Resin Gel Trimethylsiloxyphenyl Dimethicone Belsil PDM 20 6.00 Wacker Dimethicone Belsil DM 100 14.00 Wacker Caprylic/Capric Triglyceride Miglyol 812 7.00 Sasol Cyclomethicone (and) Quaternium-90 Tixogel VSP-1438 5.00 BYK Bentonite (and) Propylene Carbonate Phase B Effect pigment from 30.00 example 3

The effect pigment from example 3 can be used within a range from 5% to 30.0% by weight, based on the total weight of the eyeshadow formulation. Compensation to 100% by weight of the formulation can be effected with isohexadecane.

Phase A was mixed and heated to 85° C., then phase B was added to phase A while stirring. After dispensing into an appropriate container, the mixture is cooled to room temperature.

Application Example 3: Shower Gel

INCI name Product name % by wt. Manufacturer/supplier Phase A Effect pigment from 0.10 example 5 Aqua Water 58.50 Acrylates Copolymer Carbopol Aqua SF-1 5.50 Lubrizol Phase B Sodium Hydroxide NaOH (10% by wt.) 1.50 Phase C Sodium Laureth Sulfate Zetesol NL-2 U 22.00 Zschimmer & Schwarz Cocamidopropyl Betaine Amphotensid B5 6.00 Zschimmer & Schwarz PEG-7 Glyceryl Cocoate Emanon HE 2.00 Kao Corp. Disodium Laureth Sulfosuccinate Sectacin 103 Spezial 2.00 Zschimmer & Schwarz Phase D Phenoxyethanol (and) Piroctone Nipaguard PO 5 0.60 Clariant Olamine Fragrance Water Lily OA 0.20 Bell Flavors and Fragrances Sodium Chloride Sodium Chloride 1.60 VWR

The effect pigment from example 5 can be used within a range from 0.01% to 1.0% by weight, based on the total weight of the shower gel formulation. Compensation to 100% by weight of the formulation can be effected with water.

Phase A was stirred, then phase B was added and stirred until a homogeneous appearance was achieved. Phase C was weighed out separately, mixed briefly and added to phase AB. Subsequently, the mixture was stirred again and phase D was added individually.

Application Example 4: Eyeshadow Compact

INCI name Product name % by wt. Manufacturer/supplier Phase A Talc Talc Powder 36.00 VWR Bentonite Optigel CK-PC 5.00 BYK Synthetic Fluorphlogopite Synafil S 1050 13.00 ECKART Aluminum Starch Octenylsuccinate Agenaflo OS 9051 10.00 Agrana Magnesium Stearate Magnesium Stearate 6.00 VWR Effect pigment from example 7 20.00 Phase B Cyclomethicone Xiameter PMX-0345 5.00 Dow Corning Octyldodecyl Stearoyl Stearate Ceraphyl 847 5.00 Ashland

The effect pigment from example 7 can be used within a range from 5.0% to 40.0% by weight, based on the total weight of the eyeshadow formulation. Compensation to 100% by weight of the formulation can be effected with talc.

Phase A was mixed in a high-speed mixer at 2500 rpm for 30 s. Subsequently, phase B was added and the mixture was stirred in the same mixer at 3000 rpm for 60 s. Finally, the powder mixture is pressed into shape by means of an eyeshadow press at 100 bar for 30 seconds.

Application Example 5: Mascara

INCI name Product name % by wt. Manufacturer/supplier Phase A Aqua Water 73.00 Bentonite (and) Xanthan Gum Optigel WX-PC 2.00 BYK Phase B Cetyl Alcohol (and) Glyceryl Stearate (and) Emulium Delta 5.00 Gattefosse PEG-75 Stearate (and) Ceteth-20 (and) Steareth-20 C10-18 Triglycerides Lipocire A Pellets 2.00 Gattefosse Ozokerite Kahlwax 1899 2.00 Kahl Glyceryl Behenate Compritol 888 CG 2.00 Gattefosse Pastilles Butylene Glycol Cocoate Cocoate BG 4.00 Gattefosse Phase C Effect pigment 5.00 from example 7 Phenoxyethanol (and) Piroctone Olamine Nipaguard PO5 0.50 Clariant Glycine Soja (Soybean) Oil, Dicaprylyl Ether, Follicusan DP 3.00 CLR Berlin Magnolia Grandiflora Bark Extract, Lauryl Alcohol Water, Hydrolyzed Corn Starch, Beta Vulgaris DayMoist CLR 1.00 CLR Berlin (Beet) Root Extract Linoleic Acid (and) Linolenic Acid Vitamin F forte 0.50 CLR Berlin

The effect pigment from example 7 can be used within a range from 1.0% to 10.0% by weight, based on the total weight of the mascara formulation. Compensation to 100% by weight of the formulation can be effected with the water from phase A.

Phase A was stirred under high shear. Phase B was weighed out separately. Phase A and phase B were heated separately to 85° C., then phase B was added to phase A. Subsequently, phase AB was cooled to 45° C. and, during the cooling, phase C was added gradually while stirring.

Application Example 6: Hair Gel

% by Manufacturer/ INCI name Product name wt. supplier Phase A Sodium Magnesium Silicate Laponite XLG 2.00 BYK (nano) Aqua Water 94.80 Phase B Effect pigment 0.10 from example 6 Citric Acid (and) Water Citric Acid (10%) 0.30 Glycerin, Water, Avena Aquarich 1.50 Rahn AG Strigosa Seed Extract, Lecithin, Potassium Sorbate, Citric Acid Fragrance Lychee & Grape 0.10 Bell Europe Methylisothiazolinone (and) Optiphen MIT 1.20 Ashland Phenethyl Alcohol (and) Plus PPG-2-Methyl Ether

The effect pigment from example 6 can be used within a range from 0.01% to 2.0% by weight, based on the total weight of the hair gel formulation. Compensation to 100% by weight of the formulation can be effected with water.

The Laponite XLG was stirred with water until phase A became clear. Then the effect pigment from example 6 was added to phase B while stirring. Subsequently, the rest of the ingredients of phase B were added gradually.

Application Example 7: Body Powder

Manufacturer/ INCI name Product name % by wt. supplier Phase A Synthetic Synafil S 1050 40.00 Eckart Fluorphlogopite Polypropylene Synafil W 1234 8.00 Eckart Bentonite Optigel CK-PC 10.00 BYK Talc Talc Powder 18.00 VWR Magnesium Stearate Magnesium Stearate 4.00 Applichem Effect pigment from 20.00 example 5

The effect pigment from example 5 can be used within a range from 0.2% to 5.0% by weight, based on the total weight of the body powder formulation. Compensation to 100% by weight of the formulation can be effected with Synafil S 1050.

Phase A was mixed and then the powder was dispensed into a suitable vessel.

Application Example 8: Lipgloss

INCI name Product name % by wt. Manufacturer/supplier Phase A Hydrogenated Polyisobutene (and) Versagel ME 75.30 Penreco Ethylene/Propylene/Styrene Copolymer (and) 750 Butylene/Ethylene/Styrene Copolymer Simmondsia Chinensis (Jojoba) Seed Oil Jojoba Oil - 2.00 BioChemica Natural Caprylyl Trimethicone Silcare 7.00 Clariant Silicone 31M50 Stearyl Dimethicone Silcare 3.20 Clariant Silicone 41M65 Hydrogenated Polydecene Dekanex 4.00 IMCD 2004 FG Isopropyl Myristate Isopropyl 4.50 VWR Myristate Phase B Effect pigment 4.00 from example 6

The effect pigment from example 6 can be used within a range from 0.10% to 8.00% by weight, based on the total weight of the lipgloss formulation. Compensation to 100% by weight of the formulation can be effected with Versagel ME 750.

Phase A was heated to 85° C., then the pigment from example 6 was added to phase B and stirred until the consistency was homogeneous, and then dispensed into a lipgloss vessel.

Application Example 9: Lipstick

INCI name Product name % by wt. Manufacturer/supplier Phase A Octyldodecanol Eutanol G 42.5 BASF Candelilla Cera Kahlwax 2039 6.00 Kahl Copernicia Cerifera (Carnauba) Wax Kahlwax 2442 6.00 Kahl Bis-Diglyceryl Polyacyladipate-2 Softisan 649 10.00 Sasol Polyisobutene Rewopal PIB 1000 10.00 Evonik Hydrogenated Polydecene Silkflo 364 NF Polydecene 5.00 Ineos C10-18 Triglycerides Lipocire A Pellets 5.00 Gattefosse Acacia Decurrens/Jojoba/Sunflower Seed Hydracire S 5.00 Gattefosse Wax/Polyglyceryl-3 Esters Tocopheryl Acetate dl-alpha-Tocopheryl Acetate 0.50 IMCD Phase B Effect pigment from example 10.00 10

The effect pigment from example 10 can be used within a range from 0.5% to 20.0% by weight, based on the total weight of the lipstick formulation. Compensation to 100% by weight of the formulation can be effected with Eutanol G.

Phase A was heated to 85° C., then phase B was added to phase A and mixed. Subsequently, this mixture was dispensed into a lipstick mold at a temperature of 75° C.

Application Example 10: Liquid Eyelid Liner

INCI name Product name % by wt. Manufacturer/supplier Phase A Aqua Water 56.90 Bentonite (and) Xanthan Gum Optigel WX-PC 1.40 Phase B Lecithin Emulmetik 100 0.10 Lucas Meyer Copernicia Cerifera Cera Kahlwax 2442 1.00 Kahl Stearic Acid Stearic Acid 3.50 Lipo Chemicals Hydrogenated Polyisobutene Panalane L14 E 5.00 Ineos Polysorbate 60 Mulsifan CPS 1.50 Zschimmer & 60 Schwarz Phase C Effect pigment 4.00 from example 2 Polyurethane-35 Baycusan C 18.00 Bayer Cosmetics 1004 Aqua and CI 77499 and Methylpropanediol and WorléeBase 8.00 Worlee Ammonium Acrylates Copolymer and AQ 77499/1 Simethicone and Caprylyl Glycol and Phenylpropanol Sodium Acrylates Copolymer Phenoxyethanol, Ethylhexylglycerin Euxyl PE 9010 0.60 Schülke & Mayr

The effect pigment from example 2 can be used within a range from 0.5% to 8.0% by weight, based on the total weight of the eyelid liner formulation. Compensation to 100% by weight of the formulation can be effected with water.

Optigel WX-PC was dispersed in water of phase A and stirred for 10 minutes. Phase A and phase B were heated separately to 80° C. Thereafter, phase B was added gradually to phase A while stirring. After cooling to 45° C., the ingredients of phase C were added gradually and the mixture was dispensed into a suitable package.

Application Example 11: Mousse

INCI name Product name % by wt. Manufacturer/supplier Phase A Cyclopentasiloxane Xiameter PMX-0245 8.60 Dow Corning Cyclosiloxane Hydrogenated Polyisobutene MC 30 4.00 Sophim Dimethicone (and) Dimethicone Dow Corning 9041 37.14 Dow Corning Crosspolymer Silicone Elastomer Blend Squalane Squalane 5.74 Impag Isononyl Isononanoate Dermol 99 10.16 Akzo International Hydrogenated Jojoba Oil Jojoba Butter LM 2.15 Desert Whale Hydrogenated Jojaba Oil Jojoba Butter HM 1.00 Desert Whale C30-45 Alkyl Methicone (and) C30-45 Dow Corning AMS-C30 1.15 Dow Corning Olefin Cosmetic Wax Stearyl Dimethicone Dow Corning 2503 0.47 Dow Corning Cosmetic Wax Cyclopentasiloxane (and) Dow Corning 670 Fluid 5.00 Dow Corning Polypropylsilsesquioxane Phase B Dimethicone/Vinyl Dimethicone Dow Corning 9506 16.02 Dow Corning Crosspolymer Powder Silica Dimethyl Silylate Covasilic 15 0.17 LCW Talc Talc Powder 5.00 Sigma-Aldrich Effect pigment from 3.00 example 4 Phase D Phenoxyethanol, Ethylhexylglycerin Euxyl PE 9010 0.40 Schülke & Mayr

The effect pigment from example 4 can be used within a range from 0.1% to 8.0% by weight, based on the total weight of the mousse formulation. Compensation to 100% by weight of the formulation can be effected with Dow Corning 9041 Elastomer.

Phase A was mixed and heated until everything had melted. Phase B was weighed out separately and mixed with a high-speed mixer at 2400 rpm for 60 s. Half of the molten phase A was added to phase B and the mixture was mixed again in the mixer at 2400 rpm for 30 s. Subsequently, the remaining portion of phase B was likewise added to phase A and the mixture was mixed again at 2400 rpm for 30 s. Lastly, phase C is added to phase AB and the mixture is mixed again in the high-speed mixer at 2400 rpm for 30 s.

Application Example 12: Nail Varnish

Manufacturer/ INCI name Product name % by wt. supplier Phase A Effect pigment from 4.00 example 6 Phase B Butylacetat (and) International Lacquers 96.00 International Ethylacetat (and) Nailpolish Base 15244 Lacquers Nitrocellulose (and) Isopropyl Alcohol

The effect pigment from example 6 can be used within a range from 0.1% to 8.0% by weight, based on the total weight of the nail varnish formulation. Compensation to 100% by weight of the formulation can be effected with International Lacquers Nailpolish.

Phase A and phase B were mixed and then dispensed into an appropriate container.

Application Example 13: Nail Varnish with Soft-Touch Effect

Manufacturer/ INCI name Product name % by wt. supplier Phase A Effect pigment from 4.00 example 1 Polypropylene Synafil W 1234 5.00 Eckart Phase B Butylacetat (and) International Lacquers 91.00 International Ethylacetat (and) Nailpolish Base 15244 Lacquers Nitrocellulose (and) Isopropyl Alcohol

The effect pigment from example 1 can be used within a range from 0.1% to 8.0% by weight, based on the total weight of the nail varnish formulation. Compensation to 100% by weight of the formulation can be effected with International Lacquers Nailpolish.

Phase A was mixed and added to phase B, and then the nail varnish was dispensed into an appropriate container.

Application Example 14: Aqueous Nail Varnish

The effect pigments from examples 1 to 7 can be used in an aqueous nail varnish according to WO 2007/115675 A2 example 1. The pigmentation level here is 0.1% to 10.0% by weight, based on the total weight of the formulation.

Application Example 15: Liquid Eyeshadow

INCI name Product name % by wt. Manufacturer/supplier Phase A Water Aqua 73.80 Glycerin Glycerin 3.00 H. Erhard Wagner Phase B PEG-800 Polyglycol 35000 S 0.60 Clariant Ammonium Aristoflex AVC 0.80 Clariant Acryloyldimethyltaurate/ VP Copolymer Acrylates Copolymer Worlee Micromer CEK 20/50 5.00 Worlee Phase C Effect pigment from example 7 10.00 Divinyldimethicone/ Dow Corning HMW 2220 Non- 6.00 Dow Corning Dimethicone Ionic Emulsion Copolymer C12-C13 Pareth-3, C12-C13 Pareth-23 Phenoxyethanol, Euxyl PE9010 0.80 Schülke & Mayr Ethylhexylglycerin

The effect pigment from example 7 can be used within a range from 0.10% to 20.00% by weight, based on the total weight of the eyeshadow formulation. Compensation to 100% by weight of the formulation can be effected with water.

Phase A was stirred, then the ingredients of phase B were added individually to phase A and stirred until the consistency was homogeneous. Thereafter, the ingredients of phase C were added individually to phase AB and the mixture was stirred until the consistency was homogeneous again.

FIG. 1: Concentration profile (line scan) using a transverse section in a scanning electron microscope with energy-dispersive microanalyzer (EDX) of example 1 prior to calcination.

FIG. 2: Concentration profile (line scan) using a transverse section in a scanning electron microscope with energy-dispersive microanalyzer (EDX) of example 1 after calcination.

FIG. 3: Scanning electron micrograph of a transverse section of an effect pigment of the invention in 50 000-fold magnification (based on Polaroid 545)

FIG. 4: Detail of the scanning electron micrograph of a transverse section from FIG. 2 with a baseline drawn in at the interface of nonmetallic substrate in platelet form—coating, and lines arranged at right angles to the baseline. “x” marks the points of intersection at the interfaces.

FIG. 5: Scanning electron micrograph of a transverse section of the titanium dioxide-coated pearlescent pigment SYMIC C261 (from ECKART GmbH) in 20 000-fold magnification (based on Polaroid 545)

FIG. 6: Schematic diagram of the spacer layer

FIG. 7: Schematic diagram of the position of the spacer layer

FIG. 8: CIE LCh color space scheme

FIG. 9: claimed color region in the CIE LCh color space 

1. A red effect pigment comprising a nonmetallic substrate in platelet form and a coating applied to the substrate, wherein the coating comprises at least one of metal oxide, metal hydroxide or metal oxide hydrate, the metal ions of the metal oxide, metal hydroxide and/or metal oxide hydrate comprise at least two different metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr, the proportion of iron ions, determined by means of XRF and calculated as the elemental iron, totals at least 17% by weight, based on the total weight of the red effect pigment, and where the hue angle h*₁₅ in the CIE LCh color space is within a range from 320° to 360° and 0° to 60°.
 2. The red effect pigment as claimed in claim 1, wherein the proportion of tin, titanium and zirconium ions totals ≦20% by weight, determined in each case by means of XRF, calculated in each case as the elemental metal and based in each case on the total weight of the red effect pigment.
 3. The red effect pigment as claimed in claim 1, wherein the proportion of metal ions selected from the group of metals consisting of Sn, Ti and Zr i. in the case of tin ions totals ≦17% by weight or ii. in the case of titanium ions totals ≦15% by weight or iii. in the case of zirconium ions totals ≦18% by weight or iv. in the case of tin and titanium ions totals ≦19% by weight, determined in each case by means of XRF, calculated in each case as the elemental metal and based in each case on the total weight of the red effect pigment.
 4. The red effect pigment as claimed in claim 1, wherein the coating includes a) optionally a layer 1 comprising or consisting of at least one of tin oxide, tin hydroxide or tin oxide hydrate, b) a layer 2 comprising at least one of metal oxide, metal hydroxide or metal oxide hydrate, c) a layer 3 comprising at least one of metal oxide, metal hydroxide or metal oxide hydrate, at least one of layers 2 and 3 comprises at least two different metal ions selected from the group of metals consisting of Fe, Sn, Ti and Zr, where at least one of the layers 2 and 3 comprises iron ions and layers 2 and 3 are interrupted by a spacer layer.
 5. The red effect pigment as claimed in claim 1, wherein the nonmetallic substrate in platelet form is selected from the group consisting of natural mica platelets, synthetic mica platelets, iron mica platelets, glass platelets, SiO₂ platelets, Al₂O₃ platelets, kaolin platelets, talc platelets, bismuth oxychloride platelets and mixtures thereof, and the nonmetallic substrate in platelet form has optionally been coated with at least one of metal oxide, metal hydroxide or metal oxide hydrate.
 6. The red effect pigment as claimed in claim 1, wherein the effect pigment comprises further layers of high and/or low refractive index and optionally at least one further spacer layer.
 7. The red effect pigment as claimed in claim 1, wherein the at least one spacer layer has a mean height h_(a) from a range from 3 nm to 120 nm.
 8. The red effect pigment as claimed in claim 1, wherein the at least one spacer layer includes connections and cavities.
 9. The red effect pigment as claimed in claim 1, wherein the at least one spacer layer has a network density of <85%.
 10. A process for producing the red effect pigment as claimed in claim 1, wherein the process comprises: (i) optionally applying an uncalcined layer comprising or consisting of at least one of tin oxide, tin hydroxide or tin oxide hydrate to the nonmetallic substrate in platelet form, (ii) sequentially applying three uncalcined layers A, B and C each consisting of or comprising at least one of metal oxide, metal hydroxide or metal oxide hydrate, where the metal ion of layers A and C respectively comprises or is at least one metal ion selected from the group of metals consisting of Fe, Ti and Zr, the metal ion of layer B comprises or is at least one metal ion selected from the group of metals consisting of Sn, Ti and Zr, at least one metal ion of layers A and/or C comprises or is an iron ion, layers A, B and C are arranged directly one on top of another, and where the at least one metal oxide, metal hydroxide and/or metal oxide hydrate applied in layer B, in relation to the metal ion, is different than the metal ion(s) of the metal oxides, metal hydroxides and/or metal oxide hydrates of layer A and layer C, (iii) calcining the product obtained in step (ii) at a temperature from a range from 400° C. to 1000° C. to obtain the red effect pigment.
 11. A process for producing the red effect pigment as claimed in claim 1, wherein the process comprises: (i) sequentially applying two uncalcined layers B and C each composed of or comprising at least one of metal oxide, metal hydroxide or metal oxide hydrate to a calcined, singly or multiply coated nonmetallic substrate, where the metal ion of layer B comprises or is at least one metal ion selected from the group of metals consisting of Ti, Sn and Zr, the metal ion of layer C comprises or is at least one metal ion selected from the group of metals consisting of Fe, Ti and Zr, at least one metal ion in the layer that directly adjoins layer B in substrate direction and/or layer C comprises or is an iron ion, layers B and C are arranged directly one on top of another, and wherein the at least one metal oxide, metal hydroxide and/or metal oxide hydrate applied in layer B is different in relation to the metal ion than the metal ion(s) of the metal oxide, metal hydroxide and/or metal oxide hydrate of layer C and of the layer that directly adjoins layer B in substrate direction, where the metal ion(s) of the metal oxide, metal hydroxide and/or metal oxide hydrate of the layer that directly adjoins layer B in substrate direction comprises or is at least one metal ion selected from the group of metals consisting of Fe, Ti and Zr, (ii) calcining the product obtained in step (i) at a temperature from a range from 400° C. to 1000° C. to obtain the red effect pigment.
 12. The process as claimed in claim 10, wherein the metal ions present in layer B diffuse at least partly into layer A and/or into layer C and/or into the layer that directly adjoins layer B in substrate direction to form the at least one spacer layer in the calcined effect pigment.
 13. The process as claimed in claim 10, wherein the two or three sequentially applied metal oxides, metal hydroxides and/or metal oxide hydrates for production of the layers B and C or the layers A, B and C do not comprise any metal ion selected from the group of the metals consisting of Si, Mg and Al.
 14. A process for producing a pigmented cosmetic formulation, plastic, film, textile, ceramic material, glass, paint, printing ink, writing ink, varnish, powder coating or as laser marking additive comprising introducing the red effect pigment of claim 1 into a cosmetic formulation, plastic, film, textile, ceramic material, glass, paint, printing ink, writing ink, varnish, powder coating or a laser marking additive.
 15. An article comprising at least one red effect pigment as claimed in claim
 1. 16. The method according to claim 11, wherein the metal ions present in layer B diffuse at least partly into layer A and/or into layer C and/or into the layer that directly adjoins layer B in substrate direction to form the at least one spacer layer in the calcined effect pigment.
 17. The process according to claim 14, wherein the functional application is laser marking, IR reflection, or photocatalysis. 